Question Some random questions

I want to do some changes to my server, but i want to know these.
1. I know a guy with a name starting with icrispy or something, is he a good developer? (Please forget about price) Is his skywars plugin stable?
2. Is popup a new feature on 1.5, or is it available through 1.4?
3. Is PM 1.5 required for people to join my server with the MCPE 0.11 and vice versa? If not, what could have gone wrong?
4. Can you let players with 0.11 and 0.10 at the same time?
Thank you if you can answer these in detail, preferably in a noob way.

1) ask to him
2) 1.5
3) yes its need if you want to use pocketmine as the software
4) no

For the first answer.... I think it is obvious that he will say yes. I want like a review of his skywars plugin/his custon plugins.

We don't even know who he is.

4 is possible in the condition someone bothers to spend days and weeks studying the different protocol (the one who has the most resources to do so, @shoghicp, already refused to do so) and trying to combine them.

icrispycoder.cf

Can't comment, paid content.

Hmm...
Something like BigBrother with the only difference that you must convert MCPE 0.11.0 packets to 0.10.5 packets and vice versa