I never blanch soft fruit. Blueberries, black and red currants just go in a plastic bag or tupperware and get frozen whole. Raspberries and blackberries need to be laid out on trays and frozen flat and separately but can then be stored in bags or tupperwares. Haven't yet tried freezing plums but I imagine the best method is to halve, stone and freeze on trays then transfer to bags for easier storage.
Strawberries do not freeze well so are best made into jam, puree/coulis or compote.
No, don't blanch soft fruit, it's perfectly OK frozen as it comes. I have some shallow plastic boxes ( from takeaway meals, I think) and find they are perfect for raspberries and blackberries. Blackcurrants and gooseberries and chopped rhubarb I just bung in a freezer bag - I don't find they clump or stick together much.
Otherwise you can cook them (e.g. gooseberries, apples, rhubarb) and thaw when you want to use them in puddings or as fruit purees.
I think with lemons and oranges it would be better to just freeze the juice. You could grate the rind to freeze separately.
You can freeze lemons, oranges and other citrus whole and then use them later to make marmalade.
Soft fruit is best best frozen whole, dusted with sugar to form a light crust then frozen whole. Lemons and oranges do not freeze well the fibres break down on freezing, thus the resultant mush. This applies to all citrus fruit. Berries freeze well if frozen whole with a light dusting of sugar. Defrosting leaves all fruit mushy to a certain extent, that because the freezing process destroys the structural fibres in any plant.
Vegetables blanch well, 2 mins max, then dunk into ice cold water to stop the cooking process, freeze straight away.