#1
Ship cores with no armor in front can clip through standard armor and advanced armor.
I have not tried with basic armor. I have done this in SP and MP.
There will be a collision style animation like you are stuck but then you pass through the armor.
Works against large ships 30,000+ blocks and Stations of any size. I am working to see if it works with smaller ships too.
#2
A shipcore at 100m/s+ can, at a right angle, go through 1 thick walls, and even thicker the higher your speed goes. It can be exploited, you could potentially enter another one's base if he doesn't use thick doors. However, since in that case a base would most likely be a homebase you're not going to do anything useful anyway so I'm keeping the priority on low.
Possible fix: Try to improve the collision mechanic a bit? not exactly sure in how far this is possible but anything could make this exploit harder to use.