Specialist tools to replace an upper arm? You need a 17 mm socket, a 15 mm socket to undo the ARB link and a balljoint splitter. That, literally, is about it. Oh, sorry, a jack and a 19mm socket to take the wheel off. Takes about 30 minutes a side for a determined amateur. Probably worth getting new ARB droplinks as well, they are probably knackered (service item really).
In theory you don't need steering realignment as there is no possible adjustment. This is not the case with the lower arms.
Ebay arms are generally awful, there are many out there with a fundamental design flaw in that the bush is bonded to both centre and outer. It generally fails within 100 miles. Birth are OK, TRW are OEM.