Sales effectiveness is what your business requires and there's no uniform formula that you can adopt to achieve the same. The first problem mentioned by you isn't about sales process, but absence of requisite capability. The problem is your inability to scope out a requirement and close the deal successfully. The capability could either be built or hired or outsourced.

Your second problem again isn't about sales process, but project planning. You aren't sure how to plan the deliverable milestone, due to which you are equally unsure of resource expectation. A part of this could be limited capability of your internal team. May be you rely on freelancers to get a part of the work done and you aren't sure of time guarantee. Once again, it's better to have a rate contract and stand alone engagement with an agency to get the work delivered.

The third problem mentioned by you is something that startups across the globe struggles with, especially services based. The best way is to decide what rate works for you guys, or the outsourced team, and decide cost per complexity of the work.

I can be of help in terms of helping you build necessary effectiveness and define critical business process. Let me know if you think hopping on a call could help.