Question 1
Lets say I combine 1 level of sohei monk to nab mounted skirmisher with a cavalier and I finish the chain for whirlwind attack (Dex 13, Int 13, Combat Expertise, Dodge, Mobility, Spring Attack, base attack bonus +4)
Mounted skirmisher
Benefit: If your mount moves its speed or less, you can still take a full-attack action.
Normal: If your mount moves more than 5 feet, you can only take an attack action.
Whirlwind attack
Benefit: When you use the full-attack action, you can give up your regular attacks and instead make one melee attack at your highest base attack bonus against each opponent within reach. You must make a separate attack roll against each opponent.
When you use the Whirlwind Attack feat, you also forfeit any bonus or extra attacks granted by other feats, spells, or abilities.
Can I combine and whirlwind attack at the end of a charge ?
Question 2 (only relevant if question 1 holds true)
If I am using a lance do I get the double weapon dam against every opponent or only on the first.
Question 3 (only relevant if question 1 holds true) let say I manage to fulfill the requirements for Gorum's swordmanship DFT (not so easy because it would also entail aligment changing from the initial sohei monk, but I am theorycrafting because hey fun stuff)... Can I use Gorums swordmanship on this whirlwind attack ?
Question 4 (maybe the most exploitative...)(Again only relevant if question 1 holds true) Let say I combine my build with a rogue scout to get scouts charge... Are all my targets flat footed and prone to me Sap mastering them the shizzle out of them or just a single target