Before going too far, it would probably be a good idea to define "nostalgic look".
As ManiacJoe mentioned, it depends upon what nostalgic look you want. Most are done with curves: flattening or washing out highlights, and bring up the deep blacks to show signs of fading (B&W & color). For color, there is the cross processing, which seems to be popular, but to me just reminds me of either bad processing or faded prints - worked too long in a photo lab correcting bad color. With this, the separate RGB curves are shifted to give (usually) blue shadows and yellow highlights, but it can be most any color combination. This can be done with the curves in LR's development module.
A nostalgic or vintage look in my mind is an image that has some of these aspects: weathered, worn, warm tones, light or airy. Many of these types of images have sun flares photo-shopped in, or there may be dandelion seeds floating in the air. In North American cinematography if the main character has a memory and the film itself covers the flashback, it is usually shown as having some of the aforementioned aspects. Sometimes the stream of scenes is hazy or warm in hue. Does this make it more clear what I'm hinting at? Nostalgic was not originally defined because I was hoping that it meant something fairly general for most artists on this forum and that because of my ambiguity, would be left to personal interpretation. When I think of "nostalgic" the phrase "memory in the mind's eye" comes to mind. Goodness I hope this will prove profitable. I really do want to know what you guys think!
A lot of what you just mentioned can only be done in Photoshop.LR isn't too good about adding effects like lens flare. The stuff you mentioned would be the application of photoshop filters to change the color of an image - warming filters. Or it could be done with solid fill layers with the opacity and blend modes adjusted. From what you mentioned, I would also imagine a reduction in contrast, so you don't have heavy blacks - done with curves.
Copy & Paste the below search string into Google:
lightroom vintage OR nostalagia
About 913,000 results
You add additional words to narrow the search, such as dreamy:
lightroom dreamy vintage OR nostalgia
About 71,900 results
Keep in mind that Lightroom Presets are simply Develop module settings saved as a Develop preset. You can make your own.