Hello from Melbourne, Australia.

I am quite new to plants, acquiring a potted Aeonium in April.
It has been sprouting happily (we're just getting to the end of winter now and it is starting to warm up) but I have now a bug and leaf damage problem, and clumps of bugs in the roots and hoped for some help about how to deal with it, preferably within the pot it is in as there is some sentimental reason.

Photos are at the end of the post.

I noticed black bugs on the leaves initially, thought they were aphids and wiped them off with water/soapy water/diluted rubbing alcohol over the past few months. More recently I have noted increasing leaf damage now extending to the whole plant, even new growths, even though I am only finding much less bugs on the leaf (2-5 bugs).

This weekend I have uncovered a shallow root while watering and noticed a whole string/clump of little greeny-yellow bugs around the root. Remembered a couple of weeks ago there were tiny ltitle insects flying around the pot.

I have no garden and this pot is in a tiled balcony. I am worried about as second pot with another aeonium in it that I acquired more recently, which I have kept about 2 feet apart. It still looks OK but I did use the same bag of soil, kept from the first time.

Google tells me root aphids are a pain to remove and I might not be able to. I guess I'm wondering,
1) What is the cause of the leaf damage, is it these things on the roots, are they related to the black aphid looking things I see on the leaves, or do I have more than 1 problem?

2) What are these bug things and are they really bad?

3) How can I (try to) get rid of them?
I have seen in the shops white oil or forms of some oil, potassium salts of fatty acids, pyrethrins, imidacloprid

4) What will happen to the plant/s (it's potted with a senacio and kalanchoe) if I take no action?

5) Should I treat the other pot at the same time, or just wait until I see problems?

Photos:
Root bugs
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Leaf bugs
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Leaf damage
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Thanks so much!