When I was using smoking it, I found it very difficult to put down the pipe. It's a very tricky habit to kick. For me, I replaced smoking with IV. Shooting 100 to 200mg gets me through the day without having to redose. So although I stopped using the pipe, I found myself with a whole new set of problems.
Only you can judge how many hits to take. I was never able to put down the pipe as I was always trying to chase a high I could never reach.
When attempting to use orally, be sure to use a scale as the effects is pretty delayed compared to smoking. Crush it into powder, dump it into an empty capsule, if not, you can wrap it into a thin ball of tissue paper and parachute. That's how I would do it because shards taste like crap. (You'd know if you licked some off your fingers before)
50 to 100mg would be decent to start with as desoxyn pills are 50mg methamphetamine per pop. Be sure to wait at least 30 mins for the effects to kick in before considering add on doses.
Be safe.