Complete unfinished Magento Site integration with eBay & Amazon & update all stock

Hi, I'm looking for a Magento/M2EPro expert. I have a working Magento eCommerce Site, this is partially setup with M2EPro to connect with eBay and Amazon. The work I require is the following: 1. Magento is out of date, so first of all needs updating to latest version. Problem with updating is explained in no.2 below. 2. M2EPro is installed and is working but I have hacked one of the core files as we sell 1/2 stock units, so the core file has been changed to only deduct 1/2 a stock unit from main stock when a half is sold. I can't remember which file it is, but have a copy somewhere and will find out and attempt to explain my changes. 3. An alternative suggestion to my method in no.2 is most welcome to enable future updating without having to re-hack the core file. 4. I started the website myself when I had more time, now I have no time and would like to have it finished off in terms of all my stock listing on the web site, ebay and Amazon. Currently only eBay is fully up to date. This would involve either a) importing my eBay listings into Magento 5. I also sell on etsy, any suggestions on a link to etsy through Magento are welcome. 6. I have a couple of Moogento extensions in the admin (these may need updating) - I would like to make use of these to process my orders, print invoices and mailing labels - we currently use Integrated labels. I can supply copy of current invoice and the way I want it to look when printed. 7. I need some way of reporting on stock levels and values in stock. I need accurate stock reporting, currently using a spreadsheet! 8. I have developed the site according to methods shown from [login to view URL] which show a method of templating magento items so that they show differently in the website, eBay and Amazon according to where they are shown - I would like this doing. 9. We have approx. 5% waste on each 1 unit of stock sold, I would like some way off accounting for this as stock is sold, i.e. sell 1.05 per each 1 unit sold and sell 0.55 per each 1/2 unit sold. I know this all sounds a lot, but aside from the website tweaking, I suspect the largest part of this would be sorting out the items descriptions. If you have any questions prior to or after bidding, I am always available, please ask, I would prefer you to ask rather than assume. thanks in advance. Ian.