Your situation will likely require more analysis from an attorney to ensure your liability is minimized.
Copying even part of an article is copyright infringement. You will be looking to make sure that your use of the articles falls under the defense of "fair use".
This is where your issue is tougher than a 'yes or no' answer. Fair use is a four-part analysis which will include things like whether your use is for-profit, how much of each article you copy, whether you made any analysis or commentary, etc. You'll need someone knowledgable in copyright law to advise you on minimizing your exposure.
You are asking the right questions, so you are on the right path. However, you need to work closely with a good copyright lawyer for an initial period to minimize your risk until you get established and develop the income to defend yourself. Commentary followed by a link to the original so the reader can review the original item is relatively safe. Adding ability for further comments makes it safer. Changing the title is likely counterproductive as it makes you look sneaky and that hurts the credibility you need. Get that IP attorney, so you can protect your stuff instead of just worrying about risk of copying others.
I am not your lawyer and you are not my client. Free advice here is without recourse and any reliance thereupon is at your sole risk. This is done without compensation as a free public service. I am licensed in IL, MO, TX and I am a Reg. Pat. Atty. so advice in any other jurisdiction is strictly general advice and should be confirmed with an attorney licensed in that jurisdiction.
You are asking a great question. The topic of linking to another page is referred to as hyperlinking. There is a lot of information available on hyperlinking and copyright infringement. Often, it is permissible as fair use. But, this is a determination made on a case by case basis and you should consult an IP attorney.