Seriously guys?

I'm all for helping new people out, but .00002 seconds of searching and you'd know the answers to these..as they've been asked about 10 billion times in the last 20 pages.

Seniority in class is by age, luck of the draw in what is offered to you. After my ATR class went through, there were hardly ANY ATRs for 3 months.

CRJ 700 fits your standard size kit bag (std=18" i believe)

And finally

The ATRs are in MIA, DFW and SJU. SJU being the most senior, MIA being the least.

It's changing rapidly though, as the ATR on the FO side is a revolving door since everyone bids the jet 2nd year (pay difference is huge)

g'luck, don't mean to sound like a jerk.