+ or - 3 hours is going to be fine, follow the moveable green buoys rather than the posts if a choice exists. I'd even attempt it at -4 or shallower on a rising tide with a decent keel, as its soft as putty below the keel, so a touch isn't gonna kill you.
The berths are generous, the yacht club is excellent, there is always some sort class dinghy event on, it seems, which is great.
Sw to f5 being blown into the bay is fine as there is a decent lee outside the entrance, south or se blowing strong is going to need to get straight in, or stay off and wait or head/ stay to the north
Conwy is a decent stop off from iom, quite difficult at night as the channel snakes and need to know exactly which green flash to head for, and not always the nearest.
Into the menai straits is easier at night IMO and plentiful free moorings available an hour or two sail past puffin. Fill yor boots on the gazillion moorings, or anchor below snowdonia.