I always use high quality gold plated connectors and would not be pleased if they oxidised as they could not be the gold I paid for. Silver will tarnish over time and is best avoid for the best possible sound. Ignore the slight electrical properties of silver over gold, remember just how thick the plating is vs the tarnishing effect on electrical properties. Tight fitting connectors should not be a problem, but connectors not in use that are to be used should be cleaned thoroughly to remove dust and other contaminants that will have settled.
Locknuts loosening is a new one on me, the clue is in the name. Locknuts that loosen have not been tightened correctly in the first place or are not Locknuts.
Fairly sensible advice for a change, but most devices will sit together quite happily, in close proximity. I've had no issues, having my Dell laptop sitting on top of my Audiolab Omnia. No overheating issues and it sounds great. Keeping contacts clean is helpful, but again, spending a lot on fancy HIFI furniture is just not necessary. I've never had screws or spikes come loose. If this does happen, then it must be paranormal activity and possibly a poltergeist messing with your kit!
A contradiction with regards equipment support compared the the last similar article.
Equipment support "Does the support being level make the kit sound better? Unless we’re talking about a turntable (or a CD player to a lesser extent) the answer is a no; but it just looks nicer – and that matters!"