The fact remains he has been stalking and intimidating you for several nights. If he needed help, I imagine he’d knock or call at a reasonable hour. Not pace around outside your home, move things, silently call you and take a piss.
Not necessarily. Having spent far too much time with incapable drunks, his behaviour could well be explained by drunken incompetence, entitlement & self absorption rather than an actual attempt intimidate.
It could be that he's homeless and has burnt his bridges elsewhere and has been sleeping in the OP's garden, or in his car nearby.
He may have tried to get in as when he's drunk, he feels it's acceptable to just break into her house to get in. (Of course that's not OK, in any shape of form, but my ex thought like this).
He may not have deliberately done silent calls, but tried to call her, missed her, then pocket called her back, or even called when too drunk to realise he'd the phone had connected.
He may have rang her bell in the middle of the night because he was too drunk to realise this is a stupid thing to do.
None of the above is meant as excuses for his behaviour or that the OP shouldn't be firm in establishing her boundaries - indeed you need to be very firm with drunks, as I'm sure the OP well knows.
But just to say, it may be that he's too much of a muppet to realise how intimidating his behaviour has been. Especially if there was a dynamic in his relationship with the OP at some point, that he was able to get away with this kind of self indulgent, poor-me behaviour. (One of my exes in particular was like this and I did let him get away with it for a long time, before I wised up. He found it hard to accept I'd moved on and wasn't going to pander to him any more, no matter how helpless he pretended to be).