All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger.
First of all, we congratulate you for the bounty of embracing Islam and we ask Allaah to make you firm and steadfast on His Religion until the Day you meet Him.
We advise you to seek beneficial knowledge, perform good deeds and attend circles of Islamic knowledge and cooperate with your righteous and pious Muslim sisters in doing good.
With regard to this money, then you are obliged to get rid of the interest which you obtained after your becoming a Muslim, but you are not obliged to get rid of the interest that you obtained before that. Allaah Says (what means): {So whoever has received an admonition from his Lord and desists may have what is past, and his affair rests with Allaah. But whoever returns [to dealing in interest or usury]-those are the companions of the Fire; they will abide therein.} [Quran 2:275]
If you are not sure about the amount of forbidden interest, then you should pay an amount by which you predominantly think that you are acquitted from sin, and you should try your best to be on the safe side. For more benefit, please refer to Fataawa 83946 and 90152.
As regards liking food, then in principle there is nothing wrong with this, as the Prophet used to like some kinds of food like pumpkin, sweets and honey …etc. This is evidence that there is no blame on just liking food. So, saying that one should stay away from these kinds of food that one likes is an act of extravagnace, but what is required is that one should be moderate in eating it. Allaah Says (what means): {O children of Adam, take your adornment at every Masjid, and eat and drink, but be not excessive. Indeed, He likes not those who commit excess.} [Quran 7:31]
As regards how to be moderate in this, it is to follow the guidance of the Prophet in that, and this is discussed in Fataawa ">163527 and 7372.
In any case, a Muslim should generally deal with these worldly matters as just means which help him prepare for the Hereafter, but they should not prevent him from what benefits him, as Allaah blamed the people whose worldly matters kept them busy from being interested in the Hereafter. Allaah Says (what means): {But you prefer the worldly life. While the Hereafter is better and more enduring.} [Quran 87: 16,17]
Concerning eating with the intention of worship, then if what is meant is seeking a reward (from Allaah), then this is possible as the scholars clarified that what is permissible can be considered as an act of obedience if it has a good intention. Their evidence for this is the statement of the Prophet : ''You do not spend anything for the Sake of Allaah only except that you would be rewarded for it even the food that you put in the mouth of your wife.”
Finally, we advise you to be kind to your father, and the best way of being kind and dutiful to him is to endeavor to make him embrace Islam by supplicating Allaah to guide him and by showing the good traits of Islam to him through your dealing and morals. In addition to this, you may seek the help of trustworthy scholars and of whatever you think may encourage him to embrace Islam and clarify the truth to him. For more benefit, please refer to Fataawa 88051, 88906 and 81979.
Allaah Knows best.