Adjusting the bridge isn’t too difficult, just gently reposition it with both hands gripping it on either side. On an acoustic instrument, you’d align the bridge with the inside notches of the f holes, but I’m not sure about your electric. As for tuning, you will have to do that pretty frequently until the strings break in, but if your pegs are slipping, you may need to get a hold of some peg compound to make them stick. Alternatively, you can use chalk on the pegs to get them to stick better. Worst case scenario, you’ll need to get new pegs and have them fitted to your violin.