There are companies which offer 'white label' warehousing solutions - they look after everything for you, and you just pay them once a month.
If you want to open your own warehouse, then a good start is to have a chat with someone in Poland about labour law.
Hi there. I specialize in recruitment, so I can help you with hiring for sure. Also I can link you with people who have experience with warehousing, etc and they can chime in. Most important thing is - you need advise regarding location (which is crucial). If location is off you will have problems with hiring, transport, deliveries, etc. The area can't be difficult to access, if so, logistic operations become complicated in stead of a smooth ride. Local contracting capability is limited, etc.
Company and bank accounts are not really a problem. The same with couriers, postal accounts - not an issue. Ping me if you want to chat.