Presumptive Taxation Queries

I have am talking about both a proprietorship and partnership involved in design, sale and rental of specialised construction equipment.

1. If turnover is less than Rs.2Cr, are there any hassles to apply under presumptive taxation and charge at 6% of Gross Receipts
2. I assume gross receipts exclude GST on rent or sale. I am also assuming GST is not part of the topline or revenue when you compute P&L
3. There are some occasional mentions where AO still asks for books of accounts despite  being under Section 44. Is that easily defendable, esp if there is a likelihood that actual profits are above 10%
4. If it’s a partnership (under Section 44), is the net income of the partnership taxed at 6% and then post tax, the profit which then gets distributed to individual partners are tax free in their income statement?
5. What are the deductible for a firm, is interest and salary to partners deductible before computing presumptive taxes?