Re: Battlefield 4 Upgrade - from standard to premium

From your profile I see that you are on PC: http://battlelog.battlefield.com/bf4/user/jeremydmarshall/ and no you will not have to redownload the base game, just download the expansion packs.

That means that the premium entitlement has already been applied to your account as soon as you redeemed the code in Origin or made your purchase via origin. In order to download your Premium content in Origin follow these instructions:

Start Origin you will be prompted to download your expansions. If this doesn't happen right click the BF4 icon in your games library and select "show game details" then on each expansion right click and select "download". After all selected expansions download you can play BF4 on the expansion packs. Then go to Battlelog, multiplayer, server browser and at the top of the page add the new expansion maps and game modes to your server browser filter settings to find games on the new maps.

Regarding the shortcut question, attachments were not included in these in previous games nor in BF4.  If you want attachments you'll have to earn them via getting kills with the weapons as in previous battlefield games.  You also cannot purchase any addons to get the scope that you want.