The soil test will let you know if liming is really necessary. You can also choose to grow crops that tolerate lower pH to lessen the amount of lime you may need. Clovers are great, but your soil may need a lot of lime and fertilizer to grow a nice plot. Other crops like winter rye or oats will do well even in poor soil with little fertilizer and lime. Other things to consider are tillage (will that disc be enough to rip up the soil?), how will you plant the seed, and how will you control the ever present weeds.

You mentioned a food plot near a stream. That may not be a good location. Most crops do not do well in wet soils. I would reconsider if that area is low and prone to having standing water.

The size of the food plots will depend on how much time and cash you would like to spend. A large plot will feed more deer for longer, but it will also take more cash to start and time to manage. You can always start smaller, experiment, see what the deer by you really like, and expand if you enjoy food plotting. Half the fun is planning what you will do different and/or next year.