sure lock knife are illeagle atm
nope, can't have a folding knife over 6" though, has to be sheeth after that. And you do need a valid reason for carrying one round, personal protection or because I felt like it not good enough.
I recommend the Browning feather weights as a sort of general purpose knife. Tis what I use out in the field and i've never had an problems
http://www.browning.com/products/catalog/family.asp?webflag_=010G&catalog_=G