Game sprites - multiple projects

Looking for an additional person to produce production quality sprite work for games. Some reference and designs are provided by me. The work is work-for-hire and all copyrights will belong to me. Deliverables: 15 scifi themed icons, 64x64pixels each, .ai or .psd files. This is a vector or raster paint type job, not pixel art look. Project starts within a week. Please provide an estimate on how long it will take you, how much changework is included in the price and how much additional work would cost (more icons, up to 70 more, may follow and I would prefer they be done by the same person). Must be able to communicate in English, understand and adhere to briefs and respect deadlines. Also let me know if you're comfortable signing a NDA and leaving full address info for tax purposes.