Before even proceeding with land preparation, plan about your future crops and the timeline to achieve that.
Yes, you can improve soil condition by seasoned cow manure (3 to 6 months old). There are mixed outcomes with fresh manure. We have seen people using fresh cow manure for coconut trees and one month old chicken manure for Onion crops (during soil preparation). But there are also information that fresh manure can cause root diseases.
On the Mixed Crop cultivation, they are plenty of information about selection of varieties and time by which the ploughing to be done for nitrogen fixation.
In long run, you need a caretaker, who needs to stay in farm to take care completely. 5 Acre is good to keep a person and with average salary of 7500 Rs. If your farm has irrigation facility, fencing, permanent farm worker and who can stay in farm, then you can proceed with integrated farming by blocking 0.5 acre with local fencing (which can make the cattle to roam freely and not disturb other crops) adding goats or sheep, cow or buffalo, chicken or duck. This way you need to start keeping green for these and you will start using the manure out of it to the farm.
Unattended farming is tough, unless you have fencing and plan of tree plantation.