Posts to a Specific Page

1-3. Give this plugin a try:

https://wordpress.org/plugins/advanced-excerpt/

2. Use:

.archive .header {
  display: none;
}

4. Change:

#recent-posts-2 li {
  border-bottom: 1px solid #ccc;
  padding: 5px 0;
}

to:

.widget-container li {
  border-bottom: 1px solid #ccc;
  padding: 5px 0;
}