For sure, A123 of lipo are lighter, can give more amps, and yeah, you can build them up in stages. Although, you want to match the cells when you put...
Attached is a scanned Kodachrome slide that I took in Panama in 1966, sourced from my computer files. On my computer the photo is 1.2 MB. So I guess...
If you're not building a race bike, and are worried about burning your bike up, don't use RC lipo. Go with LiFePO4. CALB are good, GBS are also good....