Saying something through which a yameen and nazar takes place

Q: If a person says something like: 

“Wallāhi, I promise to Allah I won’t go on Instagram. If I do, I’ll give R50 in sadaqah as the expiation for me going onto Instagram.” 

1. Does this wording constitute a yamīn (oath), a nadhr (vow), or something else according to the Hanafi madhhab? 

2. Is there any way to cancel or revoke it before breaking it? 

3. If the person were to go on Instagram, would the prescribed kaffārah for a broken oath become obligatory, or would the R50 sadaqah suffice as the expiation?

Person's dua being rejected due to consuming haraam

Q: Prophet Muhammad (ﷺ) mentioned [the case] of a man who, having journeyed far, is disheveled and dusty, and who spreads out his hands to the sky saying “O Lord! O Lord!,” while his food is haraam (unlawful), his drink is haraam, his clothing is haraam, and he has been nourished with haraam, so how can [his supplication] be answered? 

Question: 

1. Does this hadith mean that it is "impossible" according to Islam that such a person's supplication (dua) will be accepted by Allah? 

2. According to Islam, can the supplications (dua) of such a person whose income, food, clothing are haraam be accepted by Allah, not because the person deserves to have his supplications (dua) accepted, rather due to Allah's infinite kindness, generosity, mercy?

Men wearing yellow clothing

Q: I have a question regarding the ruling on yellow clothing for men. 

Some hadith mention the Prophet ﷺ forbidding garments dyed with yellow saffron (muʿaṣfar), while other discussions mention yellow clothing in general. Could you please clarify: 

1. Is the prohibition specific to garments dyed with yellow dyes such as saffron or wars? 

2. Or does it apply to any garment that is completely yellow, regardless of how the color was produced? 

3. According to the Hanafi madhhab, what is the ruling for Muslim men: haram, makruh tahrimi, makruh tanzihi, or permissible? 

4. Does the ruling differ between plain yellow clothing and clothing that is only partly yellow?