Chirag; as you can see there's no shortage of opinions on this subject of sales, sales models, sales compensation, vetting candidates, etc. As you are likely learning sales is not a simple subject to either master or manage and sales does not come in just one flavor - 'one size does NOT fit all'. You are asking a crowd of varied backgrounds and experiences to help answer a few very specific questions("is it OK to hire commission only sales people", "what contract terms should it use", etc.). These arethe wrong questions at this stage of your company and you are, IMHO, putting the cart before the horse and thus getting wildly variable answers. We (this group) has inadequate data thus you are getting answers that are all over the map. This is akin to asking: "i'm in the transportation business, so what vehicle should i buy and how much should i pay"?. Someone who's run a taxi business and assumes you are transporting people across town will tell you to buy a Prius. A guy who has run a trucking company will tell you to buy an 18 wheeler. Someone who's in the business of transporting wheat around the globe will tell you to buy a ship and the texas oil tycoon will tell you to buy a pipeline. Wrong questions + incomplete data = not-so-actionable feedback. What we do know is this:
1. "i have no sales background": That's fine, but you need to back up a bit here and do some simple analysis of what you are selling, to whom and at what price (NPV and LTV really) before you can even begin to answer the questions you are asking here and, quite frankly, you are asking the wrong questions for this stage of your company.
2. "I tried partnering with marketing agencies for my enterprise customers last year and faced failure so I'm targeting on SMB. Learned many lessons in past 2 years :)" This indicates to me that you are to a significant extent shooting in the dark. It does not surprise me in the least that this model didn't work so well. You don't hire a "marketing agency" to sell a startup product to enterprise customers and you don't hire direct sales reps to sell to SMB (unless your NPV and LTV are unusual for SMB prospects and over a certain threshold, say $10k and $20k or so respectively) - you've got it almost exactly backwards.
IMHO, rather than continuing to shoot in the dark you need to back up and do some higher-level analysis of what you are selling, to whom and for how much. Only then can you land on a proper selling model and only then can you land on whom to hire (direct sales, channel sales, no sales (and go with marketing only), commission only, salary plus recoverable draw based on commissions, equity kickers, inside sales, outside sales, a combination, etc.) and how to compensate them. Full disclosure, i am not interested in running your sales org or being a paid consultant/advisor, but i'm happy to give you some actionable pointers and help however i can.