As a general rule, you add the length and the width of the room together to get the diameter of the chandelier. It should be hung 30" - 36" above the table. Some people say to add 3" for every foot over 8' - so that would put yours at 51". I personally think that is too high for a dining table. I think 36" is a good height myself. You want the chandelier to illuminate the table and not interfere with talking. If you are planning a high centerpiece it can go a bit higher. If the cords are only 5', I expect you will need to take it to a lighting shop to be reconfigured. Usually the cords are plenty long but there is not enough chain. In that instance, the manufacturer can usually provide you with extra chain.

All the companies sell extra rods.................. when you order it you order as many rods as needed. also most come with 10 ft of cord. ( this is why sometimes its better to go to a lighting show room). If it is going over the table you should have it come about 24 - 30" off the top of the table I'm a little confused at where you are actually hanging it because you said over the coffee table, but there is a picture of a nook table.?

Recessed cans wont reflect properly over the island. The light from the higher elevation will reflect off of the lower one and create uneven surface lighting and a glare off of the drop area. You could go with a single light fixture that matches the over the sink one. Move the box closer to the drop area or center it on the island and hang the fixture low enough to light the whole island. It can be a rectangle style light that would cover more area for you if you wish!

The photos of current shop are a common rafter w/ gabled ends. I know know exactly how the trusses etc will be but I'm fairly certain they'll be less storage friendly than what I currently have. Point taken but it is what it is. I am going from 8 ft to 10 ft walls however affording me the option to build some deep/tall HD shelves down 1 or 2 sides (and if open ceiling - would have easier access to suspending supports for shelves from overhead perhaps. I currently have the silver aluminum clad sheets above and it helps with lighting. The foam would look 'splotchy' to anyone looking up - but I believe it will be a white-ish color (unless it turns yellow w/ light exposure?) yielding a simlar effect for light. I don't really care about heat even though the future split mini may offer it. I do care about cooling (Texas) and for cooling - I don't really see a downside for the open ceiling in that regard. On my current shop, when I go 'upstairs' to get something down - it's a LOT warmer up there due to heat rise. The garage doors will only rarely be open - during summer months, AC will be running pretty much all the time. I don't like the flourescent tube lights on current shop - they were cheap (years ago) but uncovered I always worry about breaking one while not paying attention. Little limited in mount options w/ only joists. But I'm sure something can be figured out for shop lighting to open rafters... I may just have the builder put the cheapest bare bones switched light fixture up there and I'll put something much nicer up at a later point. The open rafters afford a HUGE opportunity to store big things up there like bike frames and 4x8 sheets and long pipes or strips of wood... But now that I think about it - going from 8 to 10 ft makes it a little trickier to put stuff up there all other things being equal... hmmm... And I have to decide on if (and where) to put a pull down ladder or just use a step ladder. Dimensions suggest joists will run front/rear so a ladder could line up and fit between the car bays. But that's the same place I like to put pull down drop lights and power and probably lights. Sigh... it's never easy!