Leafminers are responsible for the lines within the leaves shown in the first image. These are difficult to control even with using heavy duty pesticides about three times a year, so I wouldn't advise that as you're growing edible fruit. You can remove the worst affected leaves, or all affected leaves if there are plenty of healthy leaves on the tree as well. Do not compost the leaves you remove, either burn them or dispose of them in your usual rubbish, in a bag.
The woolly stuff on the stems is woolly aphid - remove as much of it as you can with your fingers, squishing the aphids in side as you go - you can use disposable cloths or wear thin gloves. This is another pest that isn't easily dealt with by pesticides because the insects inside are protected by the woolly outside.
I can't see clearly exactly what is under the leaves with the black spots - some will be aphids, but others may be scale nymphs. Suggest you get an insecticide spray suitable for use on vegetables and fruits that kills both and spray thoroughly under the leaves and on top, till the insecticide runs off. You likely will need to repeat this - check the bottle for how often you can use the spray.
The small white fuzzy areas may be scale insect - scrape off some so you can see if there's anything inside or underneath it. If there is scale, you can actually treat this manually with a disposable cloth slightly moistened with surgical spirits or 70% alcohol, rubbing it hard over woody affected areas but not on the foliage or stems. You can get insecticides for these, but unless there's a heavy infestation of them, a few can be tolerated.
I can't tell if the tree is growing in the ground or contained in something; being restricted at the root is not ideal if its contained. Keep it well watered during hot dry spells to help it stay healthy.