I happened to be reading about vitakka/vicara and savitakka/savicara just recently, so let me just direct you to it:
Vitakka, Vicāra, Savitakka, Savicāra, and Avitakka, Avicāra
About the series, I listened to them some time back, so I’ll have to relisten; it’s also about time for a review for me. I did remember that they made quite an impression on me, so they are the first ones I think about when someone asks about Dhamma talks.
Lal would know what karmastthanas means, but I am guessing that it is Kammathana in Pali, meaning object of meditation, if I’m not mistaken.
I am Vietnamese, and I’m striving to learn Pali like everyone on this site. It is indeed a joy in studying this website: learning Buddha Dhamma according to the Tipitaka, and having someone like Lal explaining the Pali terms to us.
One more addition regarding Dhamma talks: search for Dharmayai Obai from YouTube. Someone here once introduced that, and I remember listening to a few in English; they are also consistent to the Dhamma we are learning here.