1) & 2) Library, pick up pretty much all the official publisher-promo freebies in case I might want to give one of them a try, wait for deep-discount sale and stock up on books of the type that I typically read and the blurb/sample looks interesting/reads well.
But really, it's mainly the library.
PS. If you like sleuthy-to-thriller mysteries and haven't already seen this, Poisoned Pen Press has an excellent
Build Your Library introductory sale deal with currently 23 of their start-of-series books, DRM-free in a Mobi/ePub bundle when bought directly from them, for only 99 cents each.
I've bought the lot (last year's offerings and this month's additions) and enjoyed 6 out of 10 read so far enough to recommend, and the other 4 were decent enough reads.