BHAVAS
Swati: What will the significant things that come in play when 1st house placements are rahu ketu?

As Nodes afflicts Akasha Tattwa it usually gives bad education or lack of inspiration to learn. It should be confirmed with Jupiter position. Jupiter in D9 shows how one learns through God help, D24 how one learns in area or for para-/apara siddhi.

Nodes shows also ending point of education and this should be studied with 4L - goal which one would like to reach in educational spheres of life. Lagna is Brahma-sthana where one is awaken to create new possibilites therefore kendra to Lagna in Padakrama Dasa (southern name) shows new beginings to You while Kendra to Surya shows new begining to outside resources..Lagna in every Varga shows fame and attitude related to that area therefore Sani in D20-Ascendent give sadness in spiritual matters. Rahu will give too much thinking while Ketu overconfidence.
Swati:Upchaya houses are always beyond overcontrol. Is this why 11th house is considered natural badhaksthan? When dual lagna or fixed lagna is rising, how does 11th house work?I have eleventh lord in seventh bhava. It gives religiousity (ninth is distance) but also it gives too many control in my relations and they burn due to that. This control comes through karak medium - protection (ma). So its Over (11L) protection(ma) which gives troubles to reasoning (7h) and death to friend circle (11L). This also cause unpredictable (pisaca) problems (badhak) due to desires (kendra), but this makes one very good at occult and mantra (these graha are in kona to karakamsa - 3 grahas!). Mangal is not so bad as exalted in Trimsamsa-Shastyamsa.

Prashant: Bhavas from Lagna shows how we approach relationship?

Bhavas shows Bhavana - approach to area of life. If You have Mangal in tenth bhava then You want to finish things quickly, while Mangal in seventh shows too much protectivness which forms Kuja Dosha. So relationship is usually seen by comparing two lords - usually Lagnesh and Lord of person which we want to see. That is propostion from Mantreswar author of Sarwartha Cintaman