... So it's important to waterproof as much as I can all the room....
Is the room a wet room or is the shower in it's own space? If the room is a wet room then the primary wet area needs to be waterproofed and any walls waterproofed up to about 6' off of grease. The bathroom floor should be a shower pan with waterproofing coming up the walls in the non wet area atleast 6".
The base is concrete slab (all walls are interior), then should go membrane, the sloped concrete bed, then I thought red guard on floor and cement backerboards,...
You want your pre slope and then your waterproofing. After a flood test all water should drain away - make sure you check this out!
...then modified thinset and glass tiles (2x2") on the floor (and some inserts in the walls between glazed ceramic tiles).
Tiles with a mesh backer should not be used in a wet zone. Paper faced or film faced tile is better. Tiles need 95% coverage in a shower and this is not possible with most mesh backed products.
I think to use epoxy grout for the floor, but not sure if I can manage on the walls.
Epoxy is fine on the walls. What colour grout are you planning? My favourite epoxy grout is the Laticrete Spectra Lock Pro. I have only used it six times and every time I have had perfect results. For regular grout we use Ultra Colour Plus from Mapei - a fast setting grout. Typically we use Epoxy only on the floors but just yesterday used some on a vertical surface. To stiffen the mix up a hair we increased the powder portion by 10%.
The question- is the work process and material list is OK and how important to gout shower walls with epoxy too.
You better do more planning on the process. Decide on the right tile and then go about making a shower pan. The toilet connection is tricky to waterproof. Is the toilet location already roughed in?
That is all about red guard and glass tiles being not penetrable to the water, but regular grout on walls can create a problem?
Of all waterproofng liquids I've tried Red Guard is my least favourite. Liquids do not fair well with moisture rising from below. I would re-visit this plan of yours and consider using some Kerdi DS on the floor or some Noble Seal TS. Have you seen the Noble Flex Flashings? Great for tying into an exsisting three piece clamping drain. Kerdi DS is for sale in Canada but not yet the states. Noble Seal TS can be order directly from Noble Company and shipped to your door for $5.00. Email Nelson at Noble for help ordering. Nelson Wilner <firstname.lastname@example.org>
I've read a lot discussions about the glass tile on the floor, but slippage doesn't bother me, the space is too small and the shower will be used very rarely (more for emergency and guests).
A 2"x2" tile will get it's traction from the grout and the spacing between tiles. Not all glass tile is created equal. It can be very hard to install well and costly. Who will be tiling the job? I would make your installer prepare a mock up and grout it. Check the skill set of the person on the job.
Have you read my Idea Books on Houzz for choosing tile?