1. They came originally with clear? I'll go out and check, but I don't think there's any tint.
Not sure of the answer. Tinted windshields have a pretty light tint - it isn't really visible unless you put a piece of paper behind the glass and really squint.
2. I assume a new rubber gasket is mandatory. I've lost track of who has good ones - any suggestions?
When I did this operation last year, I bought a new gasket, I think from Classic Alfa. Having a soft, pliable gasket makes it easier for the new glass to go in. Which translates into a lower likelihood of breakage.
3. DIY or glass shop? Normally everything on these cars gets done by us owner-operators, and I assume a Safelite type glass shop is unfamiliar with old style windshields, but maybe not. I see even Osso had a shop install his. I could have the glass shipped directly to the shop if I knew they could do it well.
I always trust a pro to handle glass. They don't charge that much and by the time you pay for the glass + shipping, it seems like cheap insurance. BUT you do need someone familiar with gasketed windshields. Most glass installers weren't born when the industry switched from gasketed to glue-in. I wouldn't trust chain installer like Safelite - ask a restoration shop or your car buddies who they use.
The Duetto windshield is a bit tricky to do with the dashboard in place. My installer has a good reputation, but even he said at first that the dash would need to come out so he could pull the rope downward. I said "really??", he studied the problem a little more, said he'd try it, but would get black sealant on the dash top as the rope pulled across the dash. He was right, but the sealant wiped off with no problem. My point is that an amateur might have problems here.
4. I see some very tiny Phillips screws in the stainless trim. Have you had issues with these stripping and/or finding replacements?
Those weren't a problem on my Duetto, but it has led a soft life here in California; not much rust.
5. Do you need new clips around the glass?
The clips that attach the sheetmetal above the wiper mechanism are wedged under the windshield gasket and tend to rust. You won't find out whether they are shot until the old glass comes out (most likely they are). New clips are cheap (Classic Alfa charges $3.36 apiece) - it makes sense to just replace them while you're in there. CA says you need seven and their p/n is GL016.