Is a palm router enough for routing cabinet edges?

Yes. A 1/4-inch palm router handles roundovers, chamfers, flush trimming and hinge mortises on installed cabinets. It is not the tool for heavy raised panels or deep plunge cuts.

Does it come with a battery and charger?

That depends on the kit. Many cordless tools ship as bare tools, so check the listing for whether a battery and charger are included before ordering.

What bits can I use with the 1/4-inch collet?

Any bit with a 1/4-inch shank, which covers most trim, roundover, chamfer and flush-trim bits. Bits with 1/2-inch shanks will not fit.

How does variable speed help?

Lower speeds suit large-diameter bits and heat-sensitive woods; higher speeds give cleaner cuts with small bits. Start slow and raise speed until the cut is clean.