Fix 'Invalid Post Data' issues on Magento Website - Cannot install extensions and other Magento issues

Hi All, We are looking for a skilled Magento coder to assist with a few tasks which are as follows; 1. Magento Connect Manager error ' Invalid Post Data' when trying to install extensions. We are unable to install any extensions using the Connect Manager or Putty (SSH) . 2. We have an issue with 'New Products' on our homepage where by 'Out of Stock' products are being displayed. We have disabled OOS products from within Magento admin which removes them from the navigation results etc but not on the homepage. We need that only products that are enabled and have inventory quantity of 1 or more to be displayed under the 'New Product' Banner 3. Under the 'Sales - Orders' we would like to have an additional search field from one of our Custom attributes. For example to be able to search a 'Product Name' from orders which would then display all customers which have purchased it. Coding must be done to Magento best practices. All files and data is private and we expect that these are not disclosed. Successful completion of this task is also likely to lead to further employment as we are needing a skilled Magento person to assist us as our site grows. Looking forward to your bid. Thank you.