I'm not a big fan of flying regional planes on routes you can't fly at least 3 times a day, but if you are going to do it, I would probably go with the E145s, as they have commonality with future embraer planes that will be released later.
No, they don't. The 170/190 are a separate fleet group to the 130/140. The 145 is the best of that 2nd group, the 135 & 140 are even smaller. The 145 and the CRJ100/200s are nearly identical in spec. I wouldn't touch either of them.
In past games, I'd say the ATR, Saab, Q400 and An-140 are all excellent. Good speed, cheap fuel, and 1000 NM+ range on 3 of the 4. You can fly an 800 NM route 3 times/day in the Saab, and around 600-650 NM 3 times/day in the ATR or Antonov.
With the new pax allocation and the small plane warnings, they'll still be pretty good, but it probably makes some of the smaller, longer routes less feasible. Then again, maybe not. Rome-Malaga is 835 NM, no warning in a Saab, but gives one for the other 2. Rome-Hamburg is 716 NM, no warnings in any of the 3. So a big fleet of An-140s/ATRs/Saabs covering everything of 40+ pax out to 800 NM definitely looks feasible. Just no more flying ATRs from Moscow-Madrid.