Echo Silent Song.
The amp will work with whatever is put into it, meaning any signal sent into the amplifier will be amplified (duh) and sent through the speakers. This amplification then becomes the most important box in the chain and will affect the sound the most, regardless of what is put in front of it (or behind it through the FX loop).
For distortion, I highly recommend the Chandler Tube Driver. It's out of production, but very available on eBay. I prefer the rack mount, but the pedal is great as well. Satch used the unit back in the '80's, and it's a staple of Gilmour's tone as well.
We have a store around here called Music Go 'Round. They only deal in used instruments and usually have a good stock of great used gear. I could lose my bank in that place. I bought a pristine RG520QS with an oiled finish that is out of this world. If you are concerned about life expectancy, check the shop's return policy. If they don't have one, don't buy from them.
From you last comment, you don't want to risk a 400 dollar multi-fx unit that won't work properly on your amp. I would have kept the $400 and used it in my amp budget. You can get great amps with on-board fx these days (Line 6, Fender, Crate, etc.) that are sounding nearly phenomenal. But, now that you have a $400 unit and you want to pair it with a great amp, your choices still aren't that limited. Hit your local shop and play through the amps. Ask if you can hook up your unit to play through. You're the buyer - if they won't accommodate your trials, they shouldn't get your money. Plug into a Mesa, and then start saving your money haha. You can settle for a Crate in the meantime.
Of course, your live situation dictates the power you'll need. If you are playing through a PA, you could probably get by with your Frontman mic'ed through the PA. Try it out and see what happens. Otherwise, you need to get a better idea of the power requirements. Sixty Watts is probably sufficient, but who can resist 100?
