Content seo and marketing

This project is to take care of all of our seo needs. We have about 30 plus websites in all different niches that will need the following work ongoing. Link building Content writing (fresh unique and good content) also adding and changing content Marketing Updating Changes and updates to the sites Code validating Video creation All sites that can need linking to each other And more........... The main purpose of this is to increase traffic, provide good quality websites and content. and gain high rankings with search engines. many of these sites have had a lot of link building, content and marketing already and have page rank. not all sites will need to be worked on all of the time, the time will neeed to be spread beetween the sites so that everything is being covered. Please send a message if you need more detail.