If you've got a general idea about electrics it shouldn't be too much of a chore. I had some experience rewiring houses before the boat, and other general electrical experience. Nothing special.
I just started stripping wiring that had no use in my future setup. Then dissecting the rest and replacing it circuit by circuit.
All the input by ssanzone is worth gold :-)
A little bit more specific to your questions:
Some of the questions I have are:
- Do I need to change the panel?
You don't need to, but you might want to. For aesthetics, to have more switches, to have integrated breakers in your panel,... second hand ones are easy to come by, and even new ones aren't terribly expensive. But if the old one still works and doesn't show signs of heavy
corrosion, you don't have to replace ofc.
- Which wires to replace? Is it easier to rip all out and replace?
If good quality wire was used in the first place, decent joints/crimps were made and you don't see any sign of
corrosion, you don't have to replace. I did replace everything though, for peace of mind. Easiest way to do this is to think about what you want the system to be like when it's done, draw it out and go from there, one wire at a time. If you do decide to replace, do the whole shabang.
- How to run the shore
power?
Depends on what you want the system to be like

. I have a small
inverter that converts 12V to 220V for the odd time I need it on board. The shorepower is just an extension chord with a domino, takes care of all my 220V needs without too much hassle and can take a
battery charger should I need one (I'll have
solar soon).
- The AC breaker: Location, which one, etc.
These are fairly generic. IMO not too much difference between them. Mine is located close to the
alternator. Can't say why tho, but since I haven't had any problems with it, I won't be changing its location.
- Where to run the wires?
This is mostly determined by the
interior layout and the existing wiring. In my boat it's on the inside of the cabinets mostly. In my neighbor's boat, the wiring is behind some of the plastic
interior panels. They have a leak there they can't reach and it shorts out the circuit every now and again. Really depends on the boat itself. One thing to consider is that a boat is a moving, vibrating object. If you drill a hole for a cable, the cable will chafe in the hole and eventually expose the copper inside. This is very, very dangerous. Take this into account, and check it regularly.
- I ripped the old lights and purchases LED strips: where to install?
Where you want the light to shine...? This is more of a interior design question than an electrical one. Mine are behind the handrails in the
cabin shining upward, lighting the entire side of the cabin. One thing to keep in mind though: they only work from one controller if you run them in one long line. I had issues with this as I had two leads leaving the controller to both sides of the cabin. Long story though. Those bloody strips are the bane of my existence as far as boat electrics goes...