meikil by kesamim

The Mishna in nidda 58b says that a woman came to R' Akiva and asked about a kesem. He found a way to say that it came from something else and paskened l'kula. The students couldn't believe it. He said that the rabbanon only said kesamim l'kula and he quoted a pasuk to show that kesamim aren't tamei m'doraysa. The gemara on 59a asks but it's not true that the Rabonon only said kesamim l'kula. Really, kesamim should be tahor and the rabonon were machmir. The gemara said that's true - kesamim were really a chumra but it's only d'rabonon and we're meikil. The way some want to learn this gemara is that the gemara is answering that kesamim is like any other din d'rabanon that we're meikil.

A few things bothered me about this:
1. What did the students think? Did they think that kesamim were d'oraysa? Did they think that even though they're d'rabonon we're still machmir? I don't know why they'd think either of those things. (The Tosafos Yom Tov answers this question)
2. Why does R' Akiva say that the Rabonon only said kesamim l'kula. Are we changing the girsa of the Mishna? If so then what is R' Akiva's point? Just that it's a din d'rabonon? So why say "lo amru ..."
3. The Rashash points out that there is a very similar gemara in eiruvin on daf 59 (coincidentally) that has the same line about techumin. The Rashash says that the editors just "forgot" to reference that gemara here and our gemara there. Is that really likely? There are thousands and thousands of references and here it's the exact same words and they just forget to reference the other gemara in both places!?!

I think that you could answer the questions that we're not changing the girsa of the Mishna. R' Akiva meant what he said that we're meikil by kesamim. The students knew that kesamim was just a chumra d'rabonon and they knew that we should meikil by kesamim. The thing that they couldn't believe was how far R' Akiva took that. This wasn't a classic safeik. The woman came and said that she had a kesem. R' Akiva went out of his way to try find some other way that it might have been possible that the kesem came from another source. Therefore he responded that the rabonon were meikil by kesamim - even more than by normal d'rabonons. That's why this line is different from the line in Eiruvin. There the gemara only meant to say that techumin are d'rabonon and therefore we're meikil by a safeik but no more meikil than by normal d'rabonons. Here the gemara is saying much more than that. We're more meikil by kesamim than by normal d'rabonons so even if there's even just a remote chance that the kesem came from some other source we're rely on that. I'm pretty sure that this is pshat (and you may have understood it this way from the beginning) but it's not clear from the gemara.