If I change from address setting, is it going to display new address in mails that buyers get as well?
That “From” address would be used on all emails that WooCommerce sends out. So all emails your customer’s receive will be from that address.
Also, I can’t figure out how to set from address to match buyer’s address.
Is there a way to dynamically generate this email that matches email address from billing email address in checkout page?
You want the email to appear to come from the customer’s own address? There is no way to do that without customization.
Additionally, I would recommend not doing that as it will surely result in more of your emails being marked as spam and/or being rejected by the recipient’s mail server. Another factor is some public mail services do not allow you to send mail on behalf of their email addresses. So if your customer entered an @gmail.com email address, these mails would not make it to the intended recipient.
If by “buyers” you mean vendors that you actually work with for selling products, then I would recommend a different path entirely for you. In that case, I would recommend using something like the Advanced Notifications plugin. That would allow you to specify email addresses on the product level, that you would like notified when a purchase is made. This way your site would automatically let a vendor know when one of their products is purchased.
Another option would be the Product Vendors plugin. It would allow you to actually create accounts on your site for Vendors. Vendors could then list and manage their own product listings on your site. When one of their products is purchase, they would get an email notification.
I hope that information helps a bit more.