Edited by xKeisukex at 6-17-2014 10:40 PM
Boss 1 and Boss 2 does around the same damage for procs, however Boss 2 seems to do slightly more damage (few hundred to 1k) on normal attacks. The AOE proc should not mess up your proc timing enough to make any impact because you're only using 2 stun heroes (Champion and TG).
Your core 4 heroes:
Druid (tank) berserk
Succubus 3/5 Revitalize
Champion 3/5 Revitalize
TG 1/5 HB (1.5 sec stun)
Immortep 1/5 HB (1 sec stun, but higher max DPS)
Use TG for 5th hero first, and in future when your PD celebrate level is higher and the 0.5 seconds stun doesn't matter to you anymore switch to Immortep.
Executioner is not that helpful for your situation (unless it's high HB like 4/5 5/5 etc).
With your lineup the only ones possibly at risk of dying would be Druid (tanker taking more damage than the rest) / Champion (base hp might not be high enough to survive the first 2-3 boss AOE procs before Druid's heal becomes faster and more stable due to PD buff).
Lineup wise you're already using the best lineup you have. And the nice part about it is that you can conveniently drop all your 4 other heroes together once Boss aggros on your Druid (no specific drop order required).
You probably need to focus on leveling up Druid/Champion for now so that they both have more hp to survive.
Skills wise pump all your shards into PD to hit 6/9 asap (the higher the better).
Any spare gems depending on your preference should go into:
1. Trying to roll for Cupid
2. Trying to reoll for higher level talents Berserk/Revitalize etc for PD or higher level Berserk/HB Druid
3. Additional builder to hit 6th hero base asap