Thank you taurean, but I would like to read for myself aviding to disturb each one for everything xD.
I will start from arreat summit for the rest of questions.
The information and the Chart that was provided by another players is actually based on other players in the past that have posted this information from testing with multitudes of players over the years that D2 came out... the chart is actually based around v1.09 and 1.10 LoD. A dedicated group of players confirmed their results and data, combined with other sources by other players and their data, not including the people that created Bots to play D2 because they gained the information viewing the game source data.
I am not sure, but I think Quorra or the Quorra Site may still be active, it also has data, oh, by the way, Quorra is a JSP member, however when I knew him playing 1.09 to 1.13 LoD, he had a different username, he later changed his name to Quorra ... there have been other sites that people have used.
The chart shows diminishing returns ... all it means is that it loses out the higher you go, also, before in 1.08 or 09, before some patch updates, the diminishing returns did not exist, so there were people roaming around with 1000% MF and getting made drops and poison small charms over 1,000 per 2 seconds ... and people with hacks like White items, those ludicrious Hex Charms on 1.09 ... +1 Skill, +X stats etc... have like 15 of those in your inventory and Bob isn't just your Uncle, you just tell others to "Bob Down & Kiss My A!!!"
Take it or leave it.
Also... when your Merc Kills, the Merc gains any +X% Gold or Magic Find your Character is wearing (including inventory) added, BUT, your character DOES NOT gain what the merc is carrying... UNLESS this changed in D2:R.