The short answer to all questions is "What does the contract say?"
>If the business is sold, will I get 25% of the sale price
Probably not. Back of the envelope says you'll get about 1/3 of 30%.
> What guarantees are there that the guy doing the sales will work hard at it
Look into vesting and the various forms it can take. Even with that said, none really. If you're worried about this negotiate in the contract protections.
>Who/how are decisions made, do we all need to agree
Anything can be made contractual. Having 3 people agree may be impossible. Having 2 people agree maybe unfair. Plan accordingly.
>Should the software exist only on my server
This is a great protection from them stealing it. Of course, you might have legal recourse if they do, but why risk it?
>What costs can be off set against the company
I think you're talking taxation, as in write offs. Talk to an accountant. If you're asking about what can the company pay you for? Whatever the contract says.
>Can I claim extra costs for hosting on my server
Claim -- On your taxes or what? Can you bill them for the extra costs to your server? Yes, put that in the contract.
> I'm concerned that after months of development they may decide to cancel the project because of other commitments (We all have other work going on)
This is another contractual issue. You can negotiate this however you want. What you want though is a balance between giving something up to get this and protection.
>If the business is sold, will I get 25% of the sale price
Probably not. Back of the envelope says you'll get about 1/3 of 30%.
> What guarantees are there that the guy doing the sales will work hard at it
Look into vesting and the various forms it can take. Even with that said, none really. If you're worried about this negotiate in the contract protections.
>Who/how are decisions made, do we all need to agree
Anything can be made contractual. Having 3 people agree may be impossible. Having 2 people agree maybe unfair. Plan accordingly.
>Should the software exist only on my server
This is a great protection from them stealing it. Of course, you might have legal recourse if they do, but why risk it?
>What costs can be off set against the company
I think you're talking taxation, as in write offs. Talk to an accountant. If you're asking about what can the company pay you for? Whatever the contract says.
>Can I claim extra costs for hosting on my server
Claim -- On your taxes or what? Can you bill them for the extra costs to your server? Yes, put that in the contract.
> I'm concerned that after months of development they may decide to cancel the project because of other commitments (We all have other work going on)
This is another contractual issue. You can negotiate this however you want. What you want though is a balance between giving something up to get this and protection.