Corporate branding of chair professorship
You are asking too many questions in one post and most ask for opinion! Brief responses to each:


Usually faculty accept named professorships because of the increase in prestige (named-professorships are a scarce commodity and operate as such) as well as the increase in salary or research funds that usually attaches to these. Cynical people would say the latter is more important. 
Usually (almost always?) the endowment would carry an increased salary at the very least and typically additional research funds  but I have not found any statistics on the average and sd of this delta. One way to explore this is to look at the public salary data available at state-run universities in the United States and compare named vs. non-named professors at the same rank in the same department. This is left as an exercise for the reader and doesn’t account for research fund deltas. 
Yes, in that most person-based named-professorships are named after a person who most people do not know  whereas corporate names are more familiar (for example:  Prof. Mark C. Elliott, the Mark Schwartz Professor of Chinese and Inner Asian History at Harvard versus Prof Sheldon Garon, the Nissan Professor in Japanese Studies at Princeton). And thus while neither Mark Schwartz nor Nissan Motors influence the work of either faculty person, the perception is worse in the second in that we've heard of Nissan and can attribute ulterior motives to it. And as dmckee notes in the comments, humans are mortal -- while corporations are immortal. 
Note that there is a third category of alumn-class-named professorships: Cornel West, the Class of 1943 University Professor in the Center for African American Studies. These are essentially crowdfunded by a class cohort. I should note that some named fellowships are also crowdfunded — they are named in honor of so-and-so. Often the benefactor is the spouse or children, but occasionally the departure of a very-loved professor motivates students to donate. There is also a fourth category where a named professorship is created by the trustees of the university (or by the state or national government) in honor of or recognition of someone or something.