1. Contract, contract, contract. Both with the client to avoid going directly under severe penalties, both for employees (even subcontracting entities or freelancers) to scare them off such behaviour. And of course, keep your guys happy and on interesting projects, that will help nowadays more then any penalties.

2. No. Either you're end to end responsible for the development and your contract says so (and allows you for subcontractors) or you're only providing on top of cream management service, in that case they should have separate contract with those guys.

3. Design, Scalling architecture, marketing mix, R&D....you can add a lot of flavour into this. Depends on your skillset.

4. A lot. One of my companies was focused as "Foundation house", project based only, including full business development & planning services, goverment discussions around regulatory issues and management of other third parties.

Call me if you want more info, that's quite a broad topic and you probably need to have it sorted to have good client value proposition.

1. It's important to specify non-solicitation and buyout options in the contract with the client. This is something you need to put attention of your lawyers to. It will strongly depend on your country, country of your client and the laws of which country you will use in disputable cases.
2. Not sure how it's possible to sign SLA without mentioning the company name. Never saw such cases.
3. Depending on the level of the integration with the client and Agency maturity, the Agency can do pretty much everything - product, project management, UI/UX, QA, requirements... anything you can do yourself, but fail to do because of lack of right specialists.
4. The main reason why you may want to work with the Agency is the quality and expertise of their resources. Price should be always a secondary thing (unless you want to offload some simple things - like manual QA, or data labeling, or something like that). Sometimes Agency can have significantly more expertise then you have. Use it properly - and, of course, find the right Agency. Clutch is a very good data source.

I personally believe that a software agency should take the following precautions:
1. 1. There is always possibility that for future projects client will directly contact developers avoiding Agency. What precautions software development agency should take to avoid this business loss?
2. In Service Level Agreement with client for software development project is it advisable to mention development company name? If yes, what related clauses should be mentioned there.
3. What things in software development project Agency should handle itself other than software coding?
4. What value addition Agency can provide to its clients?

Besides if you do have any questions give me a call: https://clarity.fm/joy-brotonath