While we like to think of politicians as corrupt, money-grubbing jerks who'll take money from any lobbyist in order to stay in office, the truth is that most politicians already believe in certain causes and will gladly take money from their allies in those causes. The NRA is not likely to change the mind of an anti-gun senator with promises of money. That senator is likely getting money from an anti-gun group already, since that group's aims match his own. Perhaps this would be less true of corporate lobbying, but transparency could help alleviate this by letting voters see who a politicians allies are. If a politician were known to be taking Archer-Daniels money, and that politician then voted for more ethanol subsidies, I might be less likely to vote for him next time. Long story short, I don't think there is much quid-pro-quo going on, it's more an aligning of interests between pols and PACs. This is not to mention the potential freedom of speech issues of banning lobbying. After all, everyone has the right to petition the government.
2. Vote to end earmarks
This is kind of like laws against profanity - "I know it when I hear it". One man's earmark is another's worthy cause. It would be ideal if we could prevent earmarks, but defining exactly what an earmark is in such a way as to make it difficult or impossible to pass another earmark without also impacting useful legislation is practically impossible. English is a rich language that lets you say one thing and mean another in some cases, and politicians are especially adept at using the language to get what they want. Transparency is the best choice here as well, since the only sure way for "obvious" earmarks to be stopped is if the people are aware that they have been attached to unrelated bills or perverted the intentions of related bills.
3. Support publicly-financed campaigns
To me, this is the worst of all the pledges. Why should we have political welfare for people running for office? Do we really want our tax dollars spent so that some candidates can have an election allegedly free of special interests? Remember, he who controls the gold makes the rules, so public financing could be perverted into an institution that funds only "worthy" candidates, with "worthy" defined by whomever is currently in power. Even with the currently limited system for Presidential candidates, the candidates have to raise a certain amount of money and be subject to other restrictions that they find onerous. This is one reason why many of the present candidates did not accept public funding - it got in the way of raising the real sums they needed to win.
4. Support reform to increase Congressional transparency
This is one pledge I can get behind, but the devil is in the implementation. Every donation to every candidate would need to be disclosed, preferably on the web, and there would need to be dire consequences if anyone was caught trying to hide a donation or the source of a donation. Every bill, including amendments and votes, would need to be available as well. All meetings would need to be open, meaning that the press (at the least) is invited and minutes are taken and made available on-line (with reasonable exceptions for things like national security issues and maybe a few others - of course, this can be perverted as well). There are numerous documents that the government has erroneously (or illegally, if it was to CYA) classified as secret which would need to be declassified, and better oversight for what can be classified should be put into place (perhaps this is a bit beyond the scope of Congress itself). Some of these things already exist, to some degree.