Experienced Virtual Assistant / Amazon FBM/FBA and Seller Central Specialist and PPC SEM

We are a small friendly e-commerce seller, family based in the U.K with sales in UK, EU and USA
We own our own brand and have trademarked it so excellent service and product is extremely important to us.
We are looking for a long-term solution on a part-time basis initially and for around 10hour a week.
on eBay, Amazon and Shopify websites
We need help with:

1. Amazon Seller Central - listings, maintaining existing listing, keywords and search terms, making it work, managing, manipulating it, and help with social media marketing/selling private label products FBA, Sponsored Products, Enhanced Brand content
2. Shopify - helping maintain website and, listings, making it work and compatible with Amazon and vice versa and also help social media marketing.
3. eBay – Building keyword rich eBay titles, adding listings to match up with other stores and making it work the eBay way, maintaining existing listing, keywords and search terms, and help with social media marketing
4. Order processing on all platforms using Linnworks and getting it ready daily for office staff to picking and packing in the morning for postage

We need someone who is proficient in Shopify, Amazon (multiple market places) and Amazon Sponsored products and tools like Linnworks (Essential) PPCScope or similar, eBay and using eBay Listing tools (desirable but not essential).
Please send a note of interest, about you, any concerns, your experience, and anything else.