Wolf springs are great, they give you a much better trigger pull without messing with the gun's reliability. I don't like fiddling with SD guns too much, but I trust those springs since I've tested them a lot on some of my revolvers (Stalkingbear recommended them, and he knows a thing or two about Rugers!).
About the front sight, the easiest and cheapest solution would be to just paint it. If you prefer to replace it, Trijicon makes night sights for the SP101. I'm sure there are other alternatives out there as well.
Now hatred is by far the longest pleasure;
Men love in haste, but they detest at leisure.
- Lord Byron (George Gordon Noel Byron), Don Juan
(canto XII, st. 6)