Can anyone tell me if it is possible to book a trip in the one booking with 2 different destinations ie. out going shannon bergamo ( milan) and return treviso shannon, do I need to book both seperate as one way trips and pay extra credit card charges?
You must book a return leg from a different city as a separate transaction. Ryanair deliberately don't allow multi-hop bookings, as they are a point-to-point airline and don't want to be responsible for missed connections.
If I book in on line and I want to check in a bag also when I arrive at airport where do I deposit bag, do I still have to queue in check ins.
You can't check hold baggage and use Ryanair online check-in. If you pay for online checkin and later need to check baggage, you have to checkin normally at the airport, but you will get priority boarding instead (under the current rules.). That said, travelling hand luggage only is very doable with a bit of thought (perhaps harder if you are a woman though given the liquid restrictions).
If I book in on line does it mean that I can arrive at airport at a later time than usual as I have already checked in and will I be going straight to boarding? Will 45 mins before departure be ok.
Ryanair terms and conditions require you to be at boarding gate a certain time before departure (currently 30 minutes before scheduled take-off). In practice you don't actually have to be there until they start boarding (which they claim is also 30 minutes), but I suppose if they are overbooked they might strictly enforce the deadline.
You have to allow time to clear security, which will depend on the airport, time, day of week, and season. I would say 45mins is cutting it fine, unless it's a regional airport. Even then, what if some of the security points are closed or the bar code scanners don't work, so you can't use your online boarding card and have to checkin normally to get a standard boarding card? Normal checkin closes 40 mins beforehand, so I would give yourself an hour to allow for contingencies.