Some general information first: elevation ranges from 1-400. Anything under 100 is ocean. For savagery there are three 'levels' benign, neutral and savage roughly <34, 34-66, >66. (Don't remember offhand what happens at precisely 100 for elevation, or whether it is 33 or 34, 66 or 67 that is the cutoff point for savagery, not that it matters here for our purposes.)
The best way to adjust these is to use the frequency settings. The first parameter is grid size. 1 is off, 2-6 specify a size. (I recommend using 6 for a large map but you can try out others if you want - it may mean you need more extreme adjustment of the subsequent values.) The following 5 values are ratios, so 1:1:1:1:1 will split the distribution evenly, e.g. a height 1-80 will occur 20% of the time, same with each of the other height chunks. Note that this is only applied the interstices of the grid and variation is applied at all points between, hence keeping the number of these points as high as possible maximizes control over this distribution. As another example using [ELEVATION_FREQUENCY:6:1:2:2:2:3] would mean of these points only 10% would be 80 elevation or less, while 30% would be 320+. Set [END_YEAR:2] for quick generations and play around with the numbers until you are getting the proportion of oceans that you want. (You can leave your changed region counts for oceans, you just let worlds generate with no oceans!) The ocean elevation is strongly controlled by the second parameter (1 in the last example) and weakly by the third (a quarter of this elevation range will be oceans).
Now do a similar thing for savagery. Beware that this is a bit more tricky since various races have savagery requirements for settling, and it is not so easy to see at a glance. Probably using the embark finder, or manually checking savagery from the embark screen will be needed. I suggest using [SAVAGERY_FREQUENCY:6:0:0:0:0:100] (yep every point on the grid maximum savagery) but then allowing [SAVAGERY:0:100:3200:3200] to get maximum variation (can only go down from initial grid points and you should still get bits of benign savagery). If you are still not getting a savage enough world reduce the variation (the 3200's, one is x variance the other y). Once you are happy that the savagery is sufficient make sure over a few 250 year generations that all the different races have sufficient civilizations surviving well enough (on average). Otherwise you will need to adjust (one of) your expectations.
Set [ELEVATION_RANGES:0:0:0] and [SAVAGERY_RANGES:0:0:0] to avoid map rejections. I also recommend setting [SUBREGION_MAX:5000] to try to cope with the increased variation.
With beast numbers it is simply a matter of how many civilizations will get wiped out by them. I think the sky is the limit but be aware that you are likely dooming kobolds to extinction quite regularly (try upping the cave numbers to give them a slim chance). I have been using 80 semimegabeasts, 80 megabeasts, 80 titans on a small map for some time without any real problems, so that's equivalent to 1280 of each on a large map, but I remember using a lot more some time back without problems (like maybe 200 of each).
Hope that helps. I know you were asking for fish and that instead I have attempted to teach you to fish, but you will thank me in the long run.
p.s. I note you have [ELEVATION_FREQUENCY:2:2:9:9:6:6] twice...