For titanium fasteners I have used Pro-Bolt (who now have a U.S. branch at
www.probolt-usa.com) and also these guys--
http://www.racebolts.com/
Be prepared to pay top $$$ for anything in titanium, but, by the looks of your
sig you can afford it!
For a stuck screw with no real head to grab on (some hex head bolts can be
removed with good Vicegrips), you can either slot the head with a Dremel
and use a screwdriver, or drill into the stripped screw and use a tool called
an E-Z Out. There are also reverse drill bits that will sometimes back the stuck
screw out while you are drilling into it.
For fasteners that appear to be at risk of stripping (won't budge), I generally
heat the screw to soften any LocTite and then use an impact driver, which
applies a rotational force as you tap on the end of it with a mallet. It's
always more work if the head strips out, so steps like this save time in the
long run. I've had much of the Hyper apart and have yet to strip any screw.
But don't ask me about the brakes on my (Italian) Birel shifter kart...