At the last minute I decided to level as an engineer. I'm at 24 now and glad I did. For groups of trash mobs my 3s grenades + kaliyo's grenade + sweeping shot makes quick mincemeat. For bigger targets, explosive probe + cluster bombs + interrogation probe + corrosive dart gets me down to takedown territory quick - plus all those explosives are hella fun. It's very nice having that flexibility early on. For PvP though, I can see that having to go in cover to drop explosive probe - when you don't have to for interrogation probe - might get a bit annoying. Having to move up to 30m to use our best abilities eliminates some of the benefits of being a sniper too. May have to switch to lethality if I want mobility in PvP

It's really just personal choice. If you tend to die a lot because you bulldoze through stuff and you think end will make a difference, go for that. But cunning is probably more useful - just be a tad more careful or reroll a tank, maniac. ;-)

It's 35m for shots but only 30m for probes and grenades. Certain shots that have a base 10m range get extended to sniper range when you choose the sniper advanced class.

I like to log a frag grenade into a pack of mobs, then flash bang, then drop explosive probe on one, then Ambush, then another grenade. Softens up the pack pretty nicely with almost no damage to me.