Wordpress Ecommerce support to solve some issues.

I had another freelancer create this wordpress website that I need help fixing. I found some issues and the old developer is very hard to communicate with, so I help from a new freelancer. I want to tell you some of the things the old developer did so that you are aware of his work, so you can understand. The old web developer installed plugins called "Woocommerce Gateway Credit Card Offline" to allow me to collect credit card details offline. I also had the old webdeveloper install "Woocommerce Shipping UPS" to calculate the shipping using my UPS account number. IMPORTANT: The old webdoveloper told me not to update anything with Woocommerce until he instructed me, and I think maybe because he customized things. I'm not sure. He also told me never to update the theme because I think he customized it also. I can understand the theme not needing to be updated but the Woocommerce updates I feel needs to be upgraded, and I need your help to do that, but please evaluate with caution and recommend or advise what we should do. Below is a list of fixes that I need you to complete, but you will need to proceed with caution because I want you to be aware that this website has many top rankings in Google, Yahoo, and Bing, so kindly do not disrupt the content on the pages and URL setup. I need the following fixes: - I need to upgrade the "Woocommerce Shipping UPS" plugin located at [login to view URL] There is a new version that was released, and I'm a little scared to upgrade because the previous developer told me not to upgrade. I need to make this upgrade because I noticed the shipping rates are not very accurate, so this is why I need to uprade it. - I have had customers complain that the shopping cart sometimes does not work. I will need you to check it. I don't know what the previous developer did but it does not work sometimes. Maybe it is because an upgrade is needed, but just like the above, the old webdeveloper said not to upgrade until he informed me, and I don't know why, but I think maybe because of custom work. I'm not sure. - Woocommerce is not working properly, for example I noticed that the "return to shop" button has bad behaviors often. It sometimes goes to previous pages and then sometimes it goes to other pages. I think I prefer that this button go to the home page if you can not fix it. - Sometimes people searching on Google search engine click on link that is not correct. Below are samples of two URL links that people click on the Google search engine, but this is not correct links because I believe the Woocommerce maybe is not functioning very well because it has not been upgraded or installed correctly from the beginning. The following URL's are samples of incorrect URL's: "[login to view URL]" AND THIS URL [login to view URL] - Webmaster tools says that there are many broken links. Can you fix? I will provide you an Excel sheet to show you the links and the pages not found. I'm not sure why these errors exist but maybe it is the theme or the programming or maybe the fact that it has not been upgraded. - Need to remove the REDIRECTION of the product pages. Currently when somebody goes to the product page it redirects to the home page. Please do not have it redirect. I instructed the previous programmer to have all product pages redirect to the home page because I did not have all the information on the products, but I want you to remove this now because it is stopping the pages from getting indexed properly on the Search Engines. - The search on the website does not seem to work well. - Need to calculate taxes for the state of New York when selling products, and by zip code or county calculate the (Subtotal + Shipping) multiplied by the tax rate (plugin hopefully) Remember that the website is already ranked well in the Search Engines so you will need to be very careful. Good luck bidding.