I need to add some updates to my existing app

I am looking for a mobile application expert to add some new features to my existing android app. If things goes well, it can be a long term opportunity.

What I need it to do (1st update)
I need it to further calc out some numbers based off the height of stroke that it already provides. But in order to do that it would need some extra data fields for the user to enter.
1. Data fields elevation starting point/depth - This would be an elevation or feet that the pile tip sits in the ground when the piling process begins. This data field would need to count down if an elevation is provide (i.e.: elevation= 900.00 then each time the user pushed the button to mark a foot then the elevation=899.00 and so on). The data field would count up if the used chooses to enter a start point (i.e. Starting Foot/depth = 30' then each time the user pushed the button to mark a foot then the depth=31' and so on)

Further updates or second version of app (premium version?)

2. Data field weight of hammer - This number would be able to figure the energy/per blow. As I said earlier this is a simple calc of ht of stroke x weight of hammer = energy. This is not essential for this update.

3. Data field for design bearing, i.e. 170.6 tons/pile

4. Actual bearing in tons that would be another formula needed to calc based off of the height of stroke again, weight of hammer and movement of pile. I have all of these formulas readily available.

5. Data fields for specific project: Project Number/Name, structure number, pile number etc. these would show up on the report generated for the user.


Required Skills:
- Atleast 4 years of experience
- Good Communication skills
- Know GIT and SVN
- Agile Methodology

Should be proficient enough to take forward the development process with minimum assistance.