Tom, the Elmar was listed as coming with a hood, so I should be OK with that. I ordered a HeavyStar hood for the Summicron 50/2. I didn't notice any flaring when I had it out the other day, but that was under complete overcast.
I like your idea of using an extension tube, or a stack of empty filters rings.
I do use caps, mostly out of paranoia. The Summicron came with a metal Leica cap, but I may look around for a generic plastic cap. The Leica cap falls off when there's a filter on the lens, and sticks when there isn't.
The viewfinder propelled me to the M3 over the M2 or other models. I wanted something bigger after finding myself fighting the viewfinder in my R4M more than I'd like.
But, then, after I bought an big viewfinder M3 to use with my glasses, I go see my ophthalmologist this afternoon to see about the practicality of wearing contacts again.
I'm off on a short trip Friday to Albuquerque and Santa Fe (where chances for flare should abound). If the Elmar arrives by then and checks out, I may take the Leica with me, in lieu of the R4M or my OM-2N. The latter makes more sense, but I rationalize by noting that the Oly's lenses are a little bigger and heavier the Leica's'. 🙂
And, yes, you're right, a 35 would be really nice.