From deepa's POV, most of the points u have mentioned yrself gisel...
for deepa her father's words are "vedhavaaku"
she has been always insisting that she cant think of love and marriage as her family depends on her education to a large extent...but that scenario has now changed as can be seen by VR's flourishing business and the way his family is now dressed and from the way he has lined up cars along with drivers in front of lax's house..and the person behind all this- laxman...
maybe this is why they have taken time show VR's words of gratitude over and over again...his physical health and wealth are thanks to laxman...
so VR obliging laxman when in need is highly understandable and that being the case, deepa the girl she is, obliging her father is also understandable...def she is not in love clearly with anyone and now praba's case is highly sensitive..
the reason laxman suggested prabha's marriage is also that at least akhil has a family with him but with both parents jailed, prabha wd be totally lost and considering he knows that prabha and deepa know each other, the idea seems practical...there is a mandap ready, arrangements done, so quite logical thinking...
and deepa though still unclear whther to reciprocate kanagu's love or recognise her own feelings will surely want to honor her father's words... deepa's identity is with her father's..that is clear...
this is how i have understood the situation..let us see how the CTs treat it...