Yes, a 4LLL would be very beneficial to your times.
F2L:
Yes, you should practice recognition. Even better would be look-ahead. Basically, you can minimize the time you spend idly searching for the cases by searching for your next pair WHILE you're inserting your current one, not after. Many cubers (including myself before I came to this forum) take more time to search for the cases than they do to actually insert them. This is BAD, which is why you look ahead.
LL:
Yes, though you aren't able to look ahead as much. If you're using a 4LLL, it will be somewhat harder to see the EOLL and COLL coming compared to the F2L. However, try to look ahead at least a little bit and also practice speedy recognition. The CPLL and EPLL are nightmares trying to foresee, so stick to developing quick recognition skills. For the last layer in general, you would want to focus on recognition instead of look-ahead because, as you move on to a 3 to 2 LLL, your algs will become much more optimized, and, therefore, much harder to use look-ahead with.
Good luck!