Hello Maria

Your linden has 2 or 3 things going on.

Misshapen and stunted leaves were likely caused by the late frost event we had the last week of April this year. Trees that are healthy will push out new leaves over the summer if the loss due to frost was great enough.

Missing edges of leaves can be from frost damage and from some insect feeding. This is usually minor and of no concern.

Your picture with the holes shows tiny yellowish larvae in some of the holes. These larvae are eating holes in the leaves, and are likely cankerworm larvae. Use a magnifying lens and look at these insects, comparing them to images in the link, below.

While small you can control them with BT spray or insecticide. Since the linden will bloom soon and be an important source of pollinator food, BT would be your eco-friendly choice.

However, if your tree is large it will need a professional to spray it with high powered equipment. An eco-friendly option is to just tolerate the damage, and keep the tree watered during any droughty times( 2 or more weeks with no expected rain) to maintain its overall health. 
If you want to hire a professional to spray, search for a certified arborist by zip code here- http://www.treesaregood.org

Here are the details and controls for cankerworms—

https://extension.umn.edu/yard-and-garden-insects/spring-and-fall-cankerworms

If you can attach a magnifying lens to a camera or your phone camera and get some clear pictures of the larvae, we might be able to confirm the ID.

The trunk crack may be very old and in the process of being enclosed with wound wood. These cracks are typically caused by freeze/thaw cycles in winter or sunscald over the winter when the tree was young. They take many years to close up. Here is an article with more details on frost cracks and sunscald-https://www.extension.purdue.edu/extmedia/fnr/fnr-217.pdf