#2
The 3500, the wattage increase for the money is worth it. Ive played a VX3500 which is a 410 combo with a newer version if this head i guess and it was pretty good.

The cab isnt ported (as far as i can tell) so the different speaker shouldnt be a problem too. Pretty good deal imo if it all works.
"Rome wasn't built in a week"

"Yeah but when they built rome, they didnt go "hey look, there's a functional building" AND ****ING KICK IT OVER AND PISS ON THE ASHES BECAUSE THE PEASANTS WERE CRYING THAT IT WAS TOO GLORIOUS AND AWESOME."
#3
I would go with the other one but, that is just based off of the fact that I am usually weary of vintage stuff when it is sold by joe smoe. I hope this helped (P.S. I know it didn't).
#4
I'd go for the Hartke. You can never have too many watts.

Ibanez SR506BM
Ashdown Little Giant 1000w
Peavey TVX 115+410
A big ass upright