1) I might be wrong, but looking through the MT4 mql file . From what I can tell, it should actually trigger on any tick, OR on a timer (which you can change in the header). It might be that TickTime has nearly no influence on an MT4 plugin...but I might be wrong.

2) Even if it does, it's not really a 10ms delay. 10ms rather a max delay.

3) You can run a Zorro instance per broker connection to split the load (so that each Zorro occupies one CPU core) and exchange data via a global variable (https://fx1.net/sharedvar.php or implement this yourself).

4) I think the whole exercise is futile: theoretical arbitrage opportunities might exist if you trade vs. an pure MM MT4 server, but most serious brokers are STP and use more or less the same LPs. You might indeed observe a worthy price difference in MT4 but you will not be able to get filled at such prices.
MT4 introduces a significant overhead, getting to FIX makes you compete with FPGAs.