Your project sounds a lot like some facilities I have built for myself, except that
Mine is equities, not currency
My system doesn't do live trading, because I am very picky (my friends would say paranoid) about security, and I'm willing to place the trades manually.
I propose to:
Automatically collect data from your specified broker, either from a standard protocol if available or by screen scraping
Store data in a database (I prefer postgresql, but mysql is OK if you prefer)
Provide a facility to input and store your proposed strategies
Provide a facility to run simulations based on your strategies of current or historical collected data
Provide both a tracing / audit trail and a graphical view of the simulations
Do the same with live trading. I would include a capability (which could be disabled) which would require your approval before any real transaction is initiated.
I don't know what you mean by stock screeners and money management parameters, so we need to talk.
I propose three phases:
Initial payment = 25% due before I start work.
Phase 1 is agreeing on detailed specs, plus some screen mockups.
After you are happy with everything, the second 25% is due. If we can't agree on specs you are not obligated to pay the second payment, but you have no rights to the design. Alternatively you can pay but discontinue the work, in which case you own the design so far.
Phase 2 is the biggest part of the work, where I implement all of the functionality except for enabling the live trading. The third 25% is due when I first deliver this phase.
Phase 3 includes fixing any problems from phase 2, adding new or revised capabilities that we agree to, and enabling live trading. The final payment is due when this is completed.
Caveats: 1. No way will I be responsible for any losses you sustain during live trading, regardless of the cause or blame.
2. Screen scraping or other data retrieval from a non-cooperating source is inherently fragile. Companies change their web sites on average once per year, and this can break screen scraping.
I am not allowed to give you any identifying information, but I can assure you I am a very experienced and very professional developer.