How to calculate merged (dual) mining earning? and a couple questions

[alphatio]

Hi, I try to calculate the earning of merged mining such as LTC+DOGE
For Old-day Bitcoin, it's much easier with just one coin. I simply use the difficulty, block reward and my mining power. That's not a problem.

However, for combined mining, there is a combined earning of at least two coins and there are many combinations.
Let's say I have AntminerL7 (9.5 Gh) for mining LTC and DOGE.

1) Scrypt mining power is 9.5 Gh. Is it the same for DOGE?
Can I just simply the basic formula and combine it between the two
hashrate / network hashrate * number of block * block reward

2) Are there any other combos I should know. LTC+DOGE, BTC+VCASH+NMC

3) Why there is uneven proportion for earning such as in ViaBTC.
"Mine 1 BTC, get 1 NMC, 5 SYS, 0.1 EMC, 0.8 ELA as reward"
why the ratio is 1:1:5:0.1:0.8?

4) Are there any difference in "main" coin earning if there are more "sub" coins simultaneously mined.
For example, BTC+VCASH+NMC  vs  BTC+NMC+SYS+EMC+ELA
Do I earn same BTC in two cases? If so, why not everyone pool in the latter?

I've tried to workout formula and cross-check earning myself, so I do not need to rely on pool calculator.
Cannot find detailed explanation anywhere.

[JayDDee]

Merged mining is not the same as dual mining.

With merged mining you get the sum of all coins with the same hash.
With dual mining the hash is split between 2 algorithms so each gives reduced earnings.