Pine trees tend to lose their oldest (lowest) limbs with age, as they become several stories tall, so eventually they might die back on their own. If you want them to have higher branches now, though, you can have them trimmed off either this winter or next spring. Otherwise, it won't hurt the tree to keep them as-is.

The prickly weed looks like Wineberry, a fairly common invasive shrub that's related to raspberry/blackberry. As with any perennial weed, it would need to either be dug out, cut down repeatedly (every time new foliage appears, remove it promptly) until it exhausts itself, or treated with a systemic herbicide which will be absorbed by the foliage and will kill the roots. More than one treatment is sometimes needed for vigorous weeds; follow all product label instructions if you choose that approach.

Miri