They make some nice tweed looks..almost like an elegant styled berber. Lowes carries one in stock for about a buck a sq ft. Beaulieu and Shaw both carries them in their lineup.if not stocked by a retailer you will be 1.49 to a 1.59 ft I would say. Not cheap, but will out wear a normal grass for sure.

1) Like idea of removing bushes to open up. Railing a good idea once bushes are gone. Composite decking over brick questionable. Not sure about look and concerned about ventilation underneath. Brick ties together current entry area and walkway. Entry area is a small space and not sure would look right adding another material to mix. Composite is basically a mix of cardboard particles and plastic. While there has been some progress since products first introduced, (wrapping outer layer with solid plastic) cardboard particles are vulnerable to molds and can cause boards to disintegrate if particles eaten out. Without ventilation under deck, I would suspect moisture levels would be too high. It would also be rough on stringers, though if they were ground contact pressure treated wood they should be able to take it.

The largest heater you can buy that you can plug into a standard 120 V outlet is 1500 Watts. That is about 5000 BTUs of heat. That should be enough for 58.5 square feet, but you do have a lot of glass on three sides. If you are facing south or west you will be comfortable on a sunny day. A very cold night might be a problem. Amazon has dozens of heaters of all types. Read the reviews and see what you like. Most if not all have a safety tip over feature. They are supposed to shut off if the dog tips the heater. You also buy a wall mount type if there is any concern. It would also free up space for furniture.

There's a lot you can do with the front yard and steps depending on your cost. Like others have suggested, you might want to put in wider steps, maybe do stone steps with a paver pathway out to the driveway. I would encourage planting some grasses off to the right of the steps if your facing the house, not to close to the steps, and maybe put some small flowers in a bed around the grasses. It also could look good to run a flower bed from near the step across the front of your home and along the retaining wall. As for the large open space in the front and side of your yard there are so many options. You can do a few different flower beds to break up the area, including one farther out towards the curb with a tree in it to add some closure to your yard if you want. You could do planter boxes along the side of the house if you like gardening to help get some elevation away from critters. There even looks like enough space to do a small circle patio with firepit if you really want out in the middle area 45 degrees and 30-40 ft out from the retaining wall if you want though it would lack some privacy being in the front yard. So many options. Ultimately I'd check out some local landscape design firms or contractors portfolios to get some more visual ideas.