RE: Trajectory
Most crossbows are maintaince free or close to it, but the recurves are as close to it as you will ever get. Just wax your string, either reserve the wrapping or replace the string, check bolts for tightness, remove string and DP pads (dp pads for excalibur) for the off season or if going to store in a hot area.
Many of the compounds can go for many years withoutneeding service, but if ou need, you basicly need a shop unless you have ur own bow press.
Strings (mainly the serving or wrapping) on a crossbow do wear and need replacing every once in a while. If you need to replace the string on a recurve, it is a 5 minute job at most, even in the field, but on the compound, go to the proshop.
Since you state that you have always shot a compound and talk about getting new fletchings and new fletchers, most all arrow parts will work with the corssbow arrows (guess it is what you have used with your compound setup). I know many that use the same fletcher for both types of arrows. If your fletching setup requires a knock to fletch the arrow, all you need to do is glue a knock onto a field point and use fron inserts into the back of the arrow (screw it into the arrow then fletch),
Most shooters (the standard) use 4 or 5 inch veins or 5 inch feathers with either 1 to 4 degree right offset.
As for broadheads, if what you have now is a quality head, then it should work well with a quality crossbow. Where you can run into problems with hunting heads with the crossbow is if our head has a soft spine. That is, it can be easily bent (tip becomes off center from the AXIS of the arrow/head). Other then that, you will probually find that with the crossbow, ou wil not have to do all the matching, alining the blades/fletchings, ect. Some willalso tell you that if our using a fixed head with the larger cutting Dia (say 1.5"), in windy conditions, you can get some plaining of the head in flight to effect the accuracy (why some have gone to the mechanicals).
Hope this helps.