Good luck to you both!
RE: replacing fuses -- a well-respected charter member of the RItter/Easley list recommends replacing all fuses at 10-year intervals; this apparently can prevent a host of intermittant, weird electrical glitches. Fuses can LOOK good but have hairline fractures which open and close depending on temperature, current flow, moon phase, whatever. Opinions differ but most folks seem to think it's best to get ceramic fuses at an MB dealership.
RE: ignition switches, another separate issue is that it is a good idea to replace the ignition switch TUMBLER (i.e., where the key goes in) periodically, say every 100-150k miles, to prevent the very unfortunate situation where you cannot turn the key in the lock. At times this entails manually drilling out the old cylinder, which is armored and may take 8+ hours of sitting there with a drill ... These are ordered through a dealership and they'll send you a new tumbler and key which is identical to your existing ones, and usually ship overnight.