Just to make sure, a telescope and a spotting scope are quite different. While telescopes may produce images that are reversed of upside down, spotting scopes produce upright images. Most scopes are much more easier to carry, and can be easily mounted on a tripod. So make sure to get yourself a scope and not a telescope as they don’t serve the same features. However, you can use binoculars and spotting interchangeable since the scope provides a greater magnification compared to the latter. Some scopes are built waterproof, but this is not a necessary feature for all types of activities (hunting yes, birding not really). These waterproof scopes also keep the dirt and dust out of your scope!
Regarding the eyepiece, some scopes do not come with the eyepiece however, all of the options mentioned in this guide come with an eyepiece for ease and convenience. You should also be able to attach a camera to your spotting scope for digiscoping. If you require your spotting scope to support up to 100 yards, you don’t need a target shooting spotting with large objectives so, any optics with 18x-36x should offer plenty of magnification.
As for scoring beyond 100 yards, scopes with 20x-60x should do the job extremely well! If you need to go up to 300 yards, you require a stronger and larger objective of atleast 60x-80x. Anything higher requires to shell out at least 1,000$ or more. In that case, the images won’t blur as much in high magnifications compared to the more affordable spotting scopes options.