Hello Denis.
Regarding your questions, I can advise the following:
1. You are unlikely to be able to work on the patent system and you will have to register as an individual entrepreneur.
2. The tax system is better to choose a simplified: "income minus expenses." This is primarily due to the fact that under UTII you are required to pay 6% of the amount of income, which includes the amount of expenses you incurred and income received, there is no guarantee that your profit will be higher than expenses, this taxation system can be used if if in your contracts all expenses are paid directly by the Client himself and you receive a net profit, which does not always correspond to the contracts concluded in practice.
The plus of the “Income minus expenses” taxation system is that when paying a tax of 15% of the profit, from the amount received from the Client under the contract, you deduct from the income the amount of expenses that you incurred while fulfilling the contract, and pay the tax of 15% from the remaining amount . This system of taxation is used by many entrepreneurs whose profit from each contract is not more than 40-50% of the amount of the contract with the Client. The disadvantage of such a taxation system is that when submitting a tax dicloration to the Federal Tax Service, you will have to attach documents confirming expenses. The plus is that if you work to zero and the costs make up the full amount of the contract (i.e. work to zero), you will be required to pay the base tax rate, which does not exceed thousands of rubles.
3. Mandatory and fixed for all is a pension contribution to the FIU, but there is no getting around it.
4. In order not to work to zero, try to calculate all your expenses for transportation and information extraction and score them immediately in the price of the service. For these costs, throw a profit of 50 percent.
5. Better to start with physicists is easier to work with.