Hi Stu, if you BIAB then just about any domestic blender will do in a pinch but really only as a last resort. The extra flour is no biggie, I've BIABed with stone ground malt, fairly coarsely ground mind you, and blendered grain with no dramas. Same with Marga- milled stuff and commercially- milled malts, all seem to work with BIAB.
However for traditional vessel mashing with a slotted, punctured or braided manifold, you'll need the grain to be treated kindly and as intact as possible to facilitate drainage and prevent stuck sparges. Obviously some cracking of the grain is necessary to expose the kernel to liquid but too much will result in lots of flour and can lead to problems with drainage.
To answer your questions, it is pretty easy but the degree to which it needs to be cracked depends on your mashing method. Roller milling seems to be the preferred method, it leaves the husk largely intact to outward appearances but inside it is coarsely cracked. Other methods are fine for BIAB but less than perfect for manifold systems.
Freshly- ground grain is best of course, but sometimes a little bit of storage is necessary- airtight, cool and dark would be the criteria to look out for.
BTW, one of AHB's sponsors has a cheap hand- operated roller mill, about $140 + freight (~$10), is very popular with brewers and I've just bought one myself. Very pleased with it, PM me if you're having trouble finding one that's suitable.