I'll try to answer some of your questions, and there will probably be lots of differing opinions for you to choose from. BTW, welcome to the forum!
If you know the fabric content of the top (hopefully all the fabrics are the same) you could wash it on a delicate cycle with the backing. I'd use a mild detergent made for delicate fabrics - baby detergent such as Dreft, or Orvus, and dry on a low-heat cycle on delicate. You will definitely then need to press these, but at least you're not ironing in dirt, dust, etc.
Batting - that's probably a personal preference. I started out using 100% poly batting, as I liked the soft, drapy feel of it, and some say it makes for a warmer quilt. A quilt with polyester batting can't be pressed with a hot iron, though, as that stuff just melts! I am starting to use a cotton/poly blend, and if you're machine-quilting this quilt, cotton batting may be easier to work with, too.
I'll let someone else answer the machine-quilting angle - I do very little machine quilting - usually straight lines on a smallish quilt or wallhanging.
How to decide on a pattern - I think I'd look at as many finished quilts as possible to get inspiration. The pattern probably will also depend on your skill level with your machine. IMHO, curvy, feathery designs look good on quilts with alot of straight lines and more intricate piecing looks best with just basic quilting, to allow the design of the blocks show up. Can't wait to hear more about your project, and could you maybe show us a picture?

From my own personal experience, I would not recommend washing an unquilted top in the washing machine. The material will unravel and you will have threads snarled everywhere. Believe me, I did it once and unless you want to spend a day clipping tons of threads, I would not do it. Can you soak it gently in a sink just to loosen up the dirt and dust?

If you are machine quilting it, remember that polyester batting is more slippery than cotton. If you don't baste it very well, you can end up with puckering on the back. Cotton is much easier to machine quilt with.

Thanks much for the advice! So glad I didn't throw it in the machine like I wanted to! lol I hadn't even thought about the results! I'll do the sink thing, dry and iron.
Here's a picture, please keep in mind that it hasn't been washed yet and is a work in progress :o)
{{!gwi}}
Bold, isn't it? lol Yeah, and it's 5 colors, had that wrong. I've got black fabric for the backing that I'll also use to bind it.
Now I'm wondering what color thread I should use. I used black thread to piece it together... Black on the bottom and ??? for the top? I'll go with the cotton batting. Just have to measure to see how much I need.
Now I'm off to get some ideas!
And I'm going to have to try that Redwork Class too! Sounds like a lot of fun!
Thanks again for the wonderful advice and it's so nice to have you all here to help 'refresh' my quilting memory!
Cathy

Ohhhh...pretty. I'd go with varigated thread.

Welcome. I'd be a little hesitant to try to machine quilt it without a walking foot or a free motion foot. The drag would be really strong and I think you would get frustrated very quickly. If you can get a walking foot for your machine, then I think a simple diagonal grid might look nice. Otherwise you might consider machine tacking. I don't think free motion quilting would be a great idea on a quilt that size for your first attempt. I don't mean to discourage you but I don't think it's a good idea to bite off more than you can chew, if you know what I mean. In any case, the quilt has a lot of graphic appeal with those wonderful bold colors so it's a shame not to finish it in some way. Good luck and keep us posted.

i tried washing a top once and it raveled so bad I wasn't able to quilt it..I snipped threads and pressed and each time I tried to layer it I'd see more threads showing thru! Ended up using it unfinished as a throw on an old chair!

Scraphappy,
The last time I quilted, they didn't have variegated thread! lol
I picked up some new fabrics and a spool of that matching variegated thread today! I'll go and look again for some in the blue and black range for this quilt.
Fran,
I'll check into a walking foot. Hopefully at least one of the 3 machines I have will accept it. If not, I'm not too worried about it, aside from having to deal with that much bulk to quilt the middle of it.

I did keep the material in a rather clean cabinet, so really, it just needs a little rinsing and ironing.

But, before I tackle a queen sized quilt, I think I'll wet my feet again with something much smaller and test all my machines to see if they are in correct working order.
(I just quit smoking, so will treat myself to have all 3 of them taken in for cleaning, oiling, tension, adjusting or what have you, if need be! :0 )
Which reminds me to ask you all, what do you think about quilting individual squares first and then assembling them?
Seems like it would be much easier to handle, but not sure how that works...
Thanks again to all of you for your help and advice! I'm so looking forward to getting started again!
Cathy

Very pretty Cathy! I would hate to think of quilting a queen size quilt on my sewing machine. Have you thought of tying it?

I have tried many times to quilt with one color of thread on the top and another on the back. Never works, no matter how I fuss with the tension, or how slowly I quilt. I have spoken with several people who ought to know, and their advice is: Don't even try it.

Even professional long arm quilters use one color, front and back.

If you do use two different threads anyway, there will be tiny dots where the thread from other side is poking through. Even after washing, you can see the dots.

Since I tend to make two-sided quilts (designs on both sides) I'd love to be able to do it, but apparently it is not to be. I have decided that if the quilting lines are smooth enough and if the stitches are even, I don't mind seeing a contrasting thread snaking across the quilt top.

I think what you are asking about is "quilt as you go," often referred to here as QAYG. It works for me, and is a good way to go when making a large quilt on an ordinary machine. I used it for hand-quilting a double-bed quilt once, only I did it in 4 or 5 strips rather than in squares. If you do a search for QAYG, you will find a lot of threads about it. Here is one.

Here is a link that might be useful: Quilt as you go tutorial