The bec is used because the high torque servos draw too much current and can cause the esc to glitch without it or burn up the servo , it basically makes it so u get power directly from the battery rather than from the esc. The bec is essentially a voltage regulator, the
castle creations 10 amp bec is the way to go and can be found at the lhs for around 25 bucks.
If ur looking for a servo make sure u get something over 400 oz of torque, I prefer the hitec 7950 or Jr 8711.
If ur not already a member, check out rccrawler.com there's a section specifically for the lnc and lcc with lots of useful information. If it was me I would check out the for sale section on rcc for a used comp crawler transmission and then buy the flysky gt3b radio and do the hack kit that's sold on rcc (radio and hack kit less than $100), then u will have a nice radio with lots of capabilities.