Good Samaritan laws in most states should cover most anyone who is not a licensed medical professional.
Also AED's are great things and are current models are truly as automatic as they can probably be. You just open the case and follow instructions, normally in pictures, a five year old can understand. In short open the shirt, shave any chest hair where the pads will be placed (many AED's come with a disposable razor for this), give a quick once over for metal and remove it (glasses, watches, necklaces, underwire bras, etc.), remove the backing from the pads and place as indicated. From there it takes over and decides if a shock is needed and instructs you how to proceed. The most manual thing beyond prepping/placing the pads is pushing the button on some models. You shave the hair so that the pads are against the skin and do not create an ark, same for removal of metal objects. If the patient is wet try and dry them off, at least the chest between and around the pads, otherwise you run the risk of loosing part of the shock moving over the moisture on the skin, rather then through the heart where it's needed.
BTW current CPR is 30 compressions for 2 breaths, IIRC 5 cycles between checking vitals and a cycle should take about 18 seconds at the correct compression rate.
Going through updated training is always a good idea, the rates and such seem to change every few years as new results are studied. My only real beef with red cross training is they try and make it to idiot proof, I can see the perks on both ends but I wish it was slightly less so.
Check with your employer, some have designated first aid teams/staff and will pay for your training. My work has a first responder team and that's how I get my first aid, CPR/AED, and bloodborne pathogens certifications.