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Most of those things are irrelevant regarding memories. Year, month, day, for example - nothing to do with the matter. All you have to do is locate the memory you want and make sure you attach it to the correct subject and object, in the grammatical sense. In the memory: Got married to Sam, the subject is the sim whose memory it is, and the object is Sam. In the memory "Pottytrained by dad" Dad is the subject and the sim with the memory is the object. If you're not sure you've gotten it right, look at the memories in game and read the little pop-up texts, making note of any that don't read correctly.

Fiddling with memories is tedious but not especially difficult or dangerous.

7, 8, 9 and A are to do with the memory weightings and how quickly they wear off. For example, if a dear related sim dies, the sim with the memory will get the negative effect from that sim dying initially and it will wear off over time (the decay value) till it reaches a certain value (usually 0 but for things like major deaths and marriages, there is a minimum value by default). However, there is no need to adjust these values if you're adding memories - in fact, no need to adjust anything in the raw data tab unless you want to. I only adjust these values for memories if I want them to have an effect (as I did in Polgannon). If I'm just adding the memories so the 'story' is complete I don't generally bother. It's not a problem. 5 & 6 can also be adjusted but you can get round that (if you can't find the relevant codes) by just using some other suitable source for the memory. The one I alter most often is the first value - as you will know, this changes the background colour to red or green depending on whether you want a positive memory or not. I can probably tell you the suitable values for 7, 8, 9, and A if you want but I think there's an outline of them on the Sims Wiki page.

I'm not sure but I believe B makes a certain memory hidden so it can't be seen, or vice-versa.
The attraction marker is the only memory in the game that is hidden. But this isn't really useful as it'd just make the file size bigger. So don't include hidden memories.
There are also gossip memories and those kind of memories always need to be hidden. But that's something different.

Sorry - I forgot to answer this. You actually have the common values up there in your post - the only thing to think about is whether you are editing in SimPE in Hex or not. Hex values would be as follows:

100 = 64
75 = 4b
50 = 32

Edit: A, btw, since you asked above, is 10 in decimal. Hex goes 1, 2, 3, 4, 5, 6, 7, 8, 9, a, b, c, d, e, f - then 10

Negative values are something else altogether in Hex:

-100 = FF9C
-75 = FFB5
-50 = FFCE

However, you can set SimPE to work in decimal anyway so that is usually not a problem (to be awkward, I always do it in Hex). The other thing to know is that all values except 0x007 should be positive or zero. The game does its own weird calculation with the decrease value so it doesn't matter that you start with a negative value. I *think* (though I'm not sure) that the minimum value for a negative memory ends up negative even if you set it as, say, +5 - I'm not sure about that though. I'll have to check my notes.