>>423206391. Most likely.
2. 35. According to Kaphotic's datamine, there is a total of 35 Pokemon that don't appear in the games, but have their stats and models coded in.
3. Who knows? All we know is that there wasn't any hints in the direct (?) nor were they coded into the game. I hope they do return though, I really liked Naganadel.
4. Who knows? Of course we're getting shillmons back like the Garchomp and Zoroark but we don't know who they're bringing back for sure.
2. Who knows? They said more than 200+, depending on how fast their work speed is, or if they decide to make a pack #2, we could potentially get all the mons back. Funny thing is we weren't even supposed to get the mons back, before SWSH was released Masuda said that GF/Nintendo/TPC agreed that the dex cut was needed and that they weren't planning to add in the cut mons back for SWSH and future games, so really, anything is possible at this point.
5. We're definitely getting every legend (shown in datamine, it's confirmed every legend is making a comeback) and pseudo cancers from past gens. The dex cut was never about "balancing the game", and I doubt they would start caring when bringing back the mons, especially when Lando of all Pokemon were revealed.