1. Capital gains tax shall be applicable on the sale of the asset (the firm has to pay tax on the capital gains)
2. Winding up of a LLP is not as simple as it is for a partnership firm. You shall have to follow LLP (Winding Up & Dissolution )Rules 2010, which is fairly elaborate procedure.
3. Yes, salary and interest paid to partners is taxable. However, share of profit after payment of tax by LLP, is not taxable in the hand of the LLP.
If you to have a detailed professional opinion you may revert.