C++ programmer to refine the program

Information on the project
- application with GUI for working with data structures combined into a tree model;
The program is written in MFC, project in MS VS 2003 (7.10), requires Windows XP;
C++ programming language, but without adherence to the elementary principles of OOP (closer to C);
The program is compiled with static libraries.
- not used dll, ActivX, FrameWork.
- no databases are used.
- Work with Excel files is implemented through OLE (creation, opening / closing, activation of sheets, input / output of information in text format, cell formatting).
- the project is placed in the SVN repository;
There is a good user description of the tasks.

Programme summary:
The program implements an algorithm for calculating the parameters of the technical condition of the equipment. It is an advanced engineering calculator. It is not a database and has nothing to do with it.
The main element of the program is a tree structure with elements of equipment as nodes (on the left side of the window) and a changing field of input and display of information in the right part of the window. Each node has some technical information. All this is stored in a text file (txt format) in the form of data sequences separated by the sign “....” Inside the program, you can upload and download all the information from Excel.

A description of the priorities to be addressed as soon as possible (but no later than September 8-9):
1. Change (restore) of the calculation algorithm (algorithm "bit", the error is clear, it is necessary to correct it)
2. Output of certain data in Excel (into certain cells) data (the total output in Excel is organized, you need to fill the necessary cells in the Excel file generated by the program)

Description of the main tasks (for further study):
1. Development of functions of search, editing, adding data structures;
2. Modification of algorithms for data analysis and calculation of estimates;
3. processing of visual forms of data presentation and editing;
4. Import/export data to Excel file;
5. Introduction of new types of data and structures in order to apply existing algorithms for analysis and calculation of estimates to them.

Development requirements
- you can not fundamentally change the architecture of the application (rewrite again), you need to work with the existing one;
You can not use databases (SQLite, MySQL, etc.);
- static layout of libraries is required, the output must be a single executable *.exe file;

Time: the shortest possible time for priority tasks.
Further work on other tasks may need to be continued (see para. Description of the main tasks for subsequent development), but in a more gentle mode (these tasks are paid separately).
Contract price (payment will be determined by the quality and speed of the priority tasks)