Hi, and
That sounds a very nice little project you have there. I'm on the other side of the pond so can't help with things like tyres, but there's plenty more folks who can point you in the right direction.
1. Tyres - yes after 25yrs the old rubber will not be as grippy as new.
2. Belts/hoses. Nothing tricky here, all available but some are unique to the Europa so it will be easier to source them through a specialist. If all else fails, there are UK Specialists (Banks) who ship globally.
3. Engine/gearbox oil - yes, also consider air filter (inspect at least) new plugs & contact breaker points/condenser. Electronic ignition is an option but I'd wait until you have it running first. Once you have the engine fired up, personally I'd change the coolant as the antifreeze is also a corrosion inhibitor and it's well past it's sell-by-date ?
4. Brakes. Hmm. It depends how the car has spent the last 18yrs, if it's been nice & dry or subject to damp & condensation. I bought my car after a 2-3yr storage but in the UK this meant damp conditions. The brakes worked & I drove it home, but within the first month I renewed the complete system. It had external corrosion on steel brake lines, degradation on rubber hoses and corrosion on the disks. All parts are cheap (relatively) and available so why not get it 100% ?
The boosters are debatable and down to personal preference. They can stick with lack of use and you may find if you recommission the rest of the system they aren't working properly. It's usually the valves sticking and normally you can clear this. I would suggest if they work that you drive the car with them fitted and see how you get along. It's easy enough to disconnect them and check the difference in pedal feel.
The rear brake shoes retain the same friction material for servo & non-servo applications IIRC, but you can get better front pads for non-servo applications. I use EBC Greenstuff pads in my non-servo TC.
5. Bushes. IMO the front wishbone inboard bushes last well, same for the roll (sway) bar and rear lower link bushes. The plastic bushes in the lower trunnion assembly at the front often show wear and are cheap to replace with repair kits. Ball joints should be fine at this mileage.
Personally I'd just jack up each corner and feel for play at the wheel. If it's ok then I'd just drive it and see how the suspension felt because at the age of the car you can make a case for changing everything, including springs & dampers. The handling is the best part of any Lotus and I think I'd put a complete overhaul on the list of jobs for the first year, although it might not be the top priority for your cash.
Joe has collated some excellent references, workshop manuals, etc, via the forum home page which should help you to get started. When you get stuck on anything just post "help !!" and someone will be along. It's a great help if you can post pictures of the problem, so a cheap camera for the garage should be top of your list !
Brian