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Curseforge is a modding app, not a shader app. As for optifine, if you want want it when you run a modpack you download the latest Optifine version for the MC version the modpack runs on (website is optifine.net in case you don't know where to find it). Then when it downloads don't click install and instead click extract. You then either directly extract the forge mod into your modpack's mods folder or extract it to someplace you know and then move the mod into your mods folder. (the file it extracts should say the version of Optifine that it is as well as "MOD" at the end to distinguish it from the installer file) I'm hoping that what I just said is not overwhelming and you can easily follow it all. You'll also need to install your shaders manually from their respective websites.

Not possible.

This is a task for Optifine's developer, and the developer of the individual shaders. CurseForge is a platform for developers to upload their own content, CurseForge/Overwolf can't upload on their behalf.