Can't answer 1-3 since I don't do CI that often.

4 - +3 to Level of Socketed Gems -bow.

5 - Mobs that target you instead of your minions. AoE damage. How to survive: have capped resists. Make sure you have methods to deal with physical dmg like granite flask, Cast when damage taken immortal call, arctic armour etc. Make sure you look what map modifiers are active and be careful of maps with chaining/additional projectiles etc

6 - I think one streamer said, you need 3 things from your summons: dps, tanking, utility. One summon type can't really provide all 3. For example. I use SRS as damage, zombies as tanks (my zombies have 23k hp) and I take spectres as utility. "Utility spectres" like cursing necromancers. IMO spectres don't do that much dmg unless you focus on them, so I'd use them as tanks or utility but that's just my opinion as I don't do spectre-focused builds often.

7 - You need to focus your build on spectres to make them viable source of DPS. I mean outside passive skill tree. Jewels, ascendancy etc. Main issue with spectre builds is QoL with looking for those optimal spectres after every relog / spectre death

8 - equally. Spectre build can perhaps move around more as you won't have need to stay still and spam SRS, but you are not using SRS for tanking, and neither are you using spectres as tanks if you are spectre build.

9 - personally I use blasphemy + enfeeble. But main reason why ppl don't use is because they are using the reserved mana for damage auras like haste. Sacrifice survivability for clear speed. Plus unless you are SRS you are casting curses manually with ball of lightning + curse on hit for example, because you have nothing better to do with your time anyway.

10 - Summoner builds are pretty equal when it comes to how they survive, biggest differences are in playstyle, quality of life and price of putting together a viable build. Golemancer for example is in whole another price category than SRS. Choose the summoner you like to play best.