Well, here's my take on your ??s
1. those are fairly thick tiles,either embrace the "not the same look" or you'll probably need a wet saw to get them alike.
2 Med greay usually works, charcoal or black gives your colors more POP. But grout color is always the big question around here

3 The keracolor sanded from Lowe's is good.

4 clean or scrape as much of the GEII as you can, then it should be fine

5 There are a few and hopefully someone will post the names. make sure it's non-toxic to wildlife

6 Mosaicing the outside is a personal preference, You can leave it or paint it, too

7 Stands..sometimes you can buy them separate or stack terracotta pots...I'm sure more ideas will follow

You'll find lots of help here!

I have nothing to add to Shrty's great advice...I just want to whine about wanting to see a picture!!
Oh, and welcome...you're gonna like it here!

Welcome,

no dumb questions here, I am just getting started and I think all of us learn new things all the time.

I'd suggest picking up a mosaic book at the library or buying one and then just research like you said by going through this website and the many other mosaic sites out there for ideas and information.

we want pix!!!

I'm adding coin in with a 3/4" tile mosaic (direct on a premade step stone for the garden). The coin is much lower of course. Can I add grout under the coins after I have weldbonded the tiles and press the coin into it to raise the level of the coin to the level of the tile - will it stay put? I would then add the grout between the tiles 2nd. What do you think

Yes, but I wouldn't be using weldbond in any outside application. it re-hydrates and your tiles will pop loose

what glue would you suggest?

steph, I would suggest thinset and then use it as your grout too. Grout really has no adhesive qualities so pressing something into it is a hit or miss. But thinset will work great.

Thinset would be best for outside. You should also be able to build up your coins with the thinset

Below is a thread with some good advice

Here is a link that might be useful: outside

Welcome!
Stick to the thinset, once you get the hang of it it is wonderful
I repaied a vintage birdbath for a friend with a layer of thinset, let it dry, then thinset set the tessy stuff on top of that. So far it has held up for 5 years.
Thinset is great to keep your tessy stuff level.
Ok, now for the pictures?

Thanks you guys - I definitely will post a picture when I'm done. I'm a music teacher who loves to garden and is trying to add some step stones. I've always loved the mosaic ones so instead of buying premade ones or even a kit - I've set out on a creative venture...here goes.