Selling is there a default where I don’t need to enter the same shipping costs and weight

[byto253]

If you use sell similar from one of your listings it will duplicate everything in the new listing.  You can edit anything different from there. 

You can also create templates, such as "single stamps" where you fill in the tombstone information.  You can create new listings from the template and the basic information is filled in.   

[reallynicestamps]

The simplest way is to use Flat Rate Shipping.

This is particularly useful for low priced goods where Letter rates can be used.

Letters vary by weight, but if you think that most of your items will be under 100gr (or 30gr or 50 gr) you don't need to fill in anything but the shipping price.

And DON'T PANIC! you can also use Free Shipping, by putting your shipping cost into the asking price for the product.

You can upgrade to a tracked service without penalty.

While you can't print letter rate labels at home, as a stamp guy, you probably can figure out how to get around that.

[recped]

Business Policies is what you need, define a few policies that cover your normal shipping charges and then you just assign them to new listings.

https://www.ebay.ca/help/selling/business-policies/business-policies?id=4212