MXR phase 90 and guitar eq boxes. what are they

a phase 90 is neither a linear nor non-linear amplitude effect, such as gain, overdrive, (harmonic) distortion. it is a time domain effect that splits the input signal and dynamically (changing in time) shifts the phase (= very short time delay) of only one of the signals and then recombines it with the other, unaltered signal. the dynamic shifting part means the phase shift controlled by a triggering waveform generated internal to the effect (sine and/or triangle are typical) that drives the phase (short delay) shift in both + and- directions in response to the trigger or "modulating" waveform. the net effect is an ever-changing cancellation and reinforcement of the strength of the signal at different frequencies -- and the exact frequencies and the amounts of cancellations (and reinforcement) is related to current value of the delay between the dry (unaltered) and wet (delayed) signals. In short, the effect makes the signal sound "swishy" or "slushy."

for distortion/overdrive in an effect box, you are looking for something more like the Pro-co Ratt, Vox Satchurator, Ibanez Tube Screamer, Voodoo Lab Sparkle Drive ...

an EQ is not generally used to eliminate noise, though a really good parametric EQ (not your typical stompbox graphic EQ) might be able to do some selective removal of noisy bands. an EQ is usually used to fine tune the tone or timbre of the guitar -- for ex., maybe boost the highs or bass or cut ("scoop") the midrange.

Noise elimination is better done with one or more of a Noise Gate, shielding of the guitar (not an effect) or companding. the last also can make noise worse if misused.

MXR makes quality effects. however, the most popular MXR effects are relatively simple and "vintage" style. among these are the Phase 90, DynaComp, 10-band EQ and Carbon Copy Analog Delay. If you are new to guitar and effects, you might find you will get a lot more bang-for-your-buck by going with a multi-effect pedal.

I'll agree with gnease and multi-effect pedals. They give you a whole raft of effects for relatively little money (you can start well below $100). They are not the best quality effects, but they will give you the opportunity to try a lot of different combinations and decide what effects you really want/need. They are the ones that you should, then, buy as separate pedals.